diff --git a/jOOQ/src/main/java/org/jooq/BindingGetResultSetContext.java b/jOOQ/src/main/java/org/jooq/BindingGetResultSetContext.java
index dbeccf2aca..316b9ff878 100644
--- a/jOOQ/src/main/java/org/jooq/BindingGetResultSetContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingGetResultSetContext.java
@@ -68,5 +68,5 @@ public interface BindingGetResultSetContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingGetResultSetContext<T> convert(Converter<T, U> converter);
+    <T> BindingGetResultSetContext<T> convert(Converter<? super T, ? extends U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingGetSQLInputContext.java b/jOOQ/src/main/java/org/jooq/BindingGetSQLInputContext.java
index 5aab452eed..425eaaf088 100644
--- a/jOOQ/src/main/java/org/jooq/BindingGetSQLInputContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingGetSQLInputContext.java
@@ -63,5 +63,5 @@ public interface BindingGetSQLInputContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingGetSQLInputContext<T> convert(Converter<T, U> converter);
+    <T> BindingGetSQLInputContext<T> convert(Converter<? super T, ? extends U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingGetStatementContext.java b/jOOQ/src/main/java/org/jooq/BindingGetStatementContext.java
index d021a9bc21..bfb567ef0f 100644
--- a/jOOQ/src/main/java/org/jooq/BindingGetStatementContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingGetStatementContext.java
@@ -68,5 +68,5 @@ public interface BindingGetStatementContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingGetStatementContext<T> convert(Converter<T, U> converter);
+    <T> BindingGetStatementContext<T> convert(Converter<? super T, ? extends U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingRegisterContext.java b/jOOQ/src/main/java/org/jooq/BindingRegisterContext.java
index 792272633e..7f9ca6b876 100644
--- a/jOOQ/src/main/java/org/jooq/BindingRegisterContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingRegisterContext.java
@@ -64,5 +64,5 @@ public interface BindingRegisterContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingRegisterContext<T> convert(Converter<T, U> converter);
+    <T> BindingRegisterContext<T> convert(Converter<? super T, ? extends U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingSQLContext.java b/jOOQ/src/main/java/org/jooq/BindingSQLContext.java
index c80fcc8b12..216def6248 100644
--- a/jOOQ/src/main/java/org/jooq/BindingSQLContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingSQLContext.java
@@ -66,5 +66,5 @@ public interface BindingSQLContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingSQLContext<T> convert(Converter<T, U> converter);
+    <T> BindingSQLContext<T> convert(Converter<? extends T, ? super U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingSetSQLOutputContext.java b/jOOQ/src/main/java/org/jooq/BindingSetSQLOutputContext.java
index b9ae16e943..d5e7e3081c 100644
--- a/jOOQ/src/main/java/org/jooq/BindingSetSQLOutputContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingSetSQLOutputContext.java
@@ -63,5 +63,5 @@ public interface BindingSetSQLOutputContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingSetSQLOutputContext<T> convert(Converter<T, U> converter);
+    <T> BindingSetSQLOutputContext<T> convert(Converter<? extends T, ? super U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/BindingSetStatementContext.java b/jOOQ/src/main/java/org/jooq/BindingSetStatementContext.java
index 3b8ae0016e..a9617926cf 100644
--- a/jOOQ/src/main/java/org/jooq/BindingSetStatementContext.java
+++ b/jOOQ/src/main/java/org/jooq/BindingSetStatementContext.java
@@ -68,5 +68,5 @@ public interface BindingSetStatementContext<U> extends Scope {
     /**
      * Create a new context from this one using a converter.
      */
-    <T> BindingSetStatementContext<T> convert(Converter<T, U> converter);
+    <T> BindingSetStatementContext<T> convert(Converter<? extends T, ? super U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/Record.java b/jOOQ/src/main/java/org/jooq/Record.java
index b430a17efc..5516ba594c 100644
--- a/jOOQ/src/main/java/org/jooq/Record.java
+++ b/jOOQ/src/main/java/org/jooq/Record.java
@@ -1479,7 +1479,7 @@ public interface Record extends Attachable, Comparable<Record> {
      *
      * @see #get(Field, Converter)
      */
-    <T, U> U getValue(Field<T> field, Converter<? super T, U> converter) throws IllegalArgumentException,
+    <T, U> U getValue(Field<T> field, Converter<? super T, ? extends U> converter) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -1500,7 +1500,7 @@ public interface Record extends Attachable, Comparable<Record> {
      * @deprecated - 3.3.0 - [#2878] - This method will be removed in jOOQ 4.0
      */
     @Deprecated
-    <T, U> U getValue(Field<T> field, Converter<? super T, U> converter, U defaultValue)
+    <T, U> U getValue(Field<T> field, Converter<? super T, ? extends U> converter, U defaultValue)
         throws IllegalArgumentException, DataTypeException;
 
     /**
@@ -1567,7 +1567,7 @@ public interface Record extends Attachable, Comparable<Record> {
      *
      * @see {@link #get(String, Converter)}
      */
-    <U> U getValue(String fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U getValue(String fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Get a converted value from this record, providing a field name.
@@ -1586,7 +1586,7 @@ public interface Record extends Attachable, Comparable<Record> {
      * @deprecated - 3.3.0 - [#2878] - This method will be removed in jOOQ 4.0
      */
     @Deprecated
-    <U> U getValue(String fieldName, Converter<?, U> converter, U defaultValue) throws IllegalArgumentException,
+    <U> U getValue(String fieldName, Converter<?, ? extends U> converter, U defaultValue) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -1619,7 +1619,7 @@ public interface Record extends Attachable, Comparable<Record> {
      *
      * @see #get(Name, Converter)
      */
-    <U> U getValue(Name fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U getValue(Name fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Get a value from this record, providing a field index.
@@ -1685,7 +1685,7 @@ public interface Record extends Attachable, Comparable<Record> {
      *
      * @see #get(int, Converter)
      */
-    <U> U getValue(int index, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U getValue(int index, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Get a converted value from this record, providing a field index.
@@ -1704,7 +1704,7 @@ public interface Record extends Attachable, Comparable<Record> {
      * @deprecated - 3.3.0 - [#2878] - This method will be removed in jOOQ 4.0
      */
     @Deprecated
-    <U> U getValue(int index, Converter<?, U> converter, U defaultValue) throws IllegalArgumentException,
+    <U> U getValue(int index, Converter<?, ? extends U> converter, U defaultValue) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -1727,5 +1727,5 @@ public interface Record extends Attachable, Comparable<Record> {
      *
      * @see #set(Field, Object, Converter)
      */
-    <T, U> void setValue(Field<T> field, U value, Converter<T, ? super U> converter);
+    <T, U> void setValue(Field<T> field, U value, Converter<? extends T, ? super U> converter);
 }
diff --git a/jOOQ/src/main/java/org/jooq/Result.java b/jOOQ/src/main/java/org/jooq/Result.java
index 35f8e1ee0d..56fd4aae7d 100644
--- a/jOOQ/src/main/java/org/jooq/Result.java
+++ b/jOOQ/src/main/java/org/jooq/Result.java
@@ -324,7 +324,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws IllegalArgumentException If the argument field is not contained
      *             in {@link #fieldsRow()}
      */
-    <T, U> List<U> getValues(Field<T> field, Converter<? super T, U> converter) throws IllegalArgumentException;
+    <T, U> List<U> getValues(Field<T> field, Converter<? super T, ? extends U> converter) throws IllegalArgumentException;
 
     /**
      * Convenience method to fetch all values for a given field. This is
@@ -367,7 +367,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> List<U> getValues(int fieldIndex, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> List<U> getValues(int fieldIndex, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Convenience method to fetch all values for a given field. This is
@@ -410,7 +410,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> List<U> getValues(String fieldName, Converter<?, U> converter) throws IllegalArgumentException,
+    <U> List<U> getValues(String fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -454,7 +454,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> List<U> getValues(Name fieldName, Converter<?, U> converter) throws IllegalArgumentException,
+    <U> List<U> getValues(Name fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -2392,7 +2392,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> U[] intoArray(int fieldIndex, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U[] intoArray(int fieldIndex, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field name from the result.
@@ -2437,7 +2437,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> U[] intoArray(String fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U[] intoArray(String fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field name from the result.
@@ -2482,7 +2482,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> U[] intoArray(Name fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> U[] intoArray(Name fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field from the result.
@@ -2525,7 +2525,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <T, U> U[] intoArray(Field<T> field, Converter<? super T, U> converter) throws IllegalArgumentException,
+    <T, U> U[] intoArray(Field<T> field, Converter<? super T, ? extends U> converter) throws IllegalArgumentException,
         DataTypeException;
 
     /**
@@ -2562,7 +2562,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> Set<U> intoSet(int fieldIndex, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> Set<U> intoSet(int fieldIndex, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field name from the result.
@@ -2598,7 +2598,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> Set<U> intoSet(String fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> Set<U> intoSet(String fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field name from the result.
@@ -2634,7 +2634,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <U> Set<U> intoSet(Name fieldName, Converter<?, U> converter) throws IllegalArgumentException, DataTypeException;
+    <U> Set<U> intoSet(Name fieldName, Converter<?, ? extends U> converter) throws IllegalArgumentException, DataTypeException;
 
     /**
      * Return all values for a field from the result.
@@ -2668,7 +2668,7 @@ public interface Result<R extends Record> extends List<R>, Attachable {
      * @throws DataTypeException wrapping any data type conversion exception
      *             that might have occurred
      */
-    <T, U> Set<U> intoSet(Field<T> field, Converter<? super T, U> converter) throws IllegalArgumentException,
+    <T, U> Set<U> intoSet(Field<T> field, Converter<? super T, ? extends U> converter) throws IllegalArgumentException,
         DataTypeException;
 
     /**
diff --git a/jOOQ/src/main/java/org/jooq/ResultQuery.java b/jOOQ/src/main/java/org/jooq/ResultQuery.java
index 04dd92a1b9..76a932eb5e 100644
--- a/jOOQ/src/main/java/org/jooq/ResultQuery.java
+++ b/jOOQ/src/main/java/org/jooq/ResultQuery.java
@@ -281,7 +281,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Record#get(Field, Converter)
      */
-    <T, U> List<U> fetch(Field<T> field, Converter<? super T, U> converter) throws DataAccessException;
+    <T, U> List<U> fetch(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field index from the
@@ -319,7 +319,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Record#get(int, Converter)
      */
-    <U> List<U> fetch(int fieldIndex, Converter<?, U> converter) throws DataAccessException;
+    <U> List<U> fetch(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -357,7 +357,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Record#get(String, Converter)
      */
-    <U> List<U> fetch(String fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> List<U> fetch(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -395,7 +395,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Record#get(Name, Converter)
      */
-    <U> List<U> fetch(Name fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> List<U> fetch(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -437,7 +437,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <T, U> U fetchOne(Field<T> field, Converter<? super T, U> converter) throws DataAccessException, TooManyRowsException;
+    <T, U> U fetchOne(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -479,7 +479,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> U fetchOne(int fieldIndex, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> U fetchOne(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -521,7 +521,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> U fetchOne(String fieldName, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> U fetchOne(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -563,7 +563,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> U fetchOne(Name fieldName, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> U fetchOne(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting record.
@@ -705,7 +705,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, U> converter) throws DataAccessException, TooManyRowsException;
+    <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -744,7 +744,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -783,7 +783,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> Optional<U> fetchOptional(String fieldName, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> Optional<U> fetchOptional(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -822,7 +822,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @throws TooManyRowsException if the query returned more than one record
      */
-    <U> Optional<U> fetchOptional(Name fieldName, Converter<?, U> converter) throws DataAccessException, TooManyRowsException;
+    <U> Optional<U> fetchOptional(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException, TooManyRowsException;
 
     /**
      * Execute the query and return at most one resulting record.
@@ -947,7 +947,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      *         records.
      * @throws DataAccessException if something went wrong executing the query
      */
-    <T, U> U fetchAny(Field<T> field, Converter<? super T, U> converter) throws DataAccessException;
+    <T, U> U fetchAny(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -986,7 +986,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      *         records.
      * @throws DataAccessException if something went wrong executing the query
      */
-    <U> U fetchAny(int fieldIndex, Converter<?, U> converter) throws DataAccessException;
+    <U> U fetchAny(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -1025,7 +1025,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      *         records.
      * @throws DataAccessException if something went wrong executing the query
      */
-    <U> U fetchAny(String fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> U fetchAny(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return at most one resulting value for a
@@ -1064,7 +1064,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      *         records.
      * @throws DataAccessException if something went wrong executing the query
      */
-    <U> U fetchAny(Name fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> U fetchAny(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return at most one resulting record.
@@ -2774,7 +2774,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(int, Converter)
      */
-    <U> U[] fetchArray(int fieldIndex, Converter<?, U> converter) throws DataAccessException;
+    <U> U[] fetchArray(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -2816,7 +2816,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(String, Class)
      */
-    <U> U[] fetchArray(String fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> U[] fetchArray(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -2858,7 +2858,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(Name, Class)
      */
-    <U> U[] fetchArray(Name fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> U[] fetchArray(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field from the generated
@@ -2897,7 +2897,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(Field, Converter)
      */
-    <T, U> U[] fetchArray(Field<T> field, Converter<? super T, U> converter) throws DataAccessException;
+    <T, U> U[] fetchArray(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field index from the
@@ -2927,7 +2927,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(int, Converter)
      */
-    <U> Set<U> fetchSet(int fieldIndex, Converter<?, U> converter) throws DataAccessException;
+    <U> Set<U> fetchSet(int fieldIndex, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -2957,7 +2957,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(String, Class)
      */
-    <U> Set<U> fetchSet(String fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> Set<U> fetchSet(String fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field name from the
@@ -2987,7 +2987,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(Name, Class)
      */
-    <U> Set<U> fetchSet(Name fieldName, Converter<?, U> converter) throws DataAccessException;
+    <U> Set<U> fetchSet(Name fieldName, Converter<?, ? extends U> converter) throws DataAccessException;
 
     /**
      * Execute the query and return all values for a field from the generated
@@ -3017,7 +3017,7 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
      * @throws DataAccessException if something went wrong executing the query
      * @see Result#intoArray(Field, Converter)
      */
-    <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, U> converter) throws DataAccessException;
+    <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, ? extends U> converter) throws DataAccessException;
 
     /**
      * Map resulting records onto a custom type.
diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java b/jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java
index f5c119896d..b57730a012 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java
@@ -1137,13 +1137,13 @@ abstract class AbstractRecord extends AbstractStore implements Record {
     }
 
     @Override
-    public final <T, U> U getValue(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U getValue(Field<T> field, Converter<? super T, ? extends U> converter) {
         return get(field, converter);
     }
 
     @Override
     @Deprecated
-    public final <T, U> U getValue(Field<T> field, Converter<? super T, U> converter, U defaultValue) {
+    public final <T, U> U getValue(Field<T> field, Converter<? super T, ? extends U> converter, U defaultValue) {
         final U result = get(field, converter);
         return result == null ? defaultValue : result;
     }
@@ -1173,13 +1173,13 @@ abstract class AbstractRecord extends AbstractStore implements Record {
     }
 
     @Override
-    public final <U> U getValue(int index, Converter<?, U> converter) {
+    public final <U> U getValue(int index, Converter<?, ? extends U> converter) {
         return get(index, converter);
     }
 
     @Override
     @Deprecated
-    public final <U> U getValue(int index, Converter<?, U> converter, U defaultValue) {
+    public final <U> U getValue(int index, Converter<?, ? extends U> converter, U defaultValue) {
         final U result = get(index, converter);
         return result == null ? defaultValue : result;
     }
@@ -1208,13 +1208,13 @@ abstract class AbstractRecord extends AbstractStore implements Record {
     }
 
     @Override
-    public final <U> U getValue(String fieldName, Converter<?, U> converter) {
+    public final <U> U getValue(String fieldName, Converter<?, ? extends U> converter) {
         return get(fieldName, converter);
     }
 
     @Override
     @Deprecated
-    public final <U> U getValue(String fieldName, Converter<?, U> converter, U defaultValue) {
+    public final <U> U getValue(String fieldName, Converter<?, ? extends U> converter, U defaultValue) {
         final U result = get(fieldName, converter);
         return result == null ? defaultValue : result;
     }
@@ -1230,7 +1230,7 @@ abstract class AbstractRecord extends AbstractStore implements Record {
     }
 
     @Override
-    public final <U> U getValue(Name fieldName, Converter<?, U> converter) {
+    public final <U> U getValue(Name fieldName, Converter<?, ? extends U> converter) {
         return get(fieldName, converter);
     }
 
@@ -1240,7 +1240,7 @@ abstract class AbstractRecord extends AbstractStore implements Record {
     }
 
     @Override
-    public final <T, U> void setValue(Field<T> field, U value, Converter<T, ? super U> converter) {
+    public final <T, U> void setValue(Field<T> field, U value, Converter<? extends T, ? super U> converter) {
         set(field, value, converter);
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractResultQuery.java b/jOOQ/src/main/java/org/jooq/impl/AbstractResultQuery.java
index d98fd88abd..cb82200ba3 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractResultQuery.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractResultQuery.java
@@ -399,7 +399,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> List<U> fetch(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> List<U> fetch(Field<T> field, Converter<? super T, ? extends U> converter) {
         return fetch().getValues(field, converter);
     }
 
@@ -414,7 +414,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> List<U> fetch(int fieldIndex, Converter<?, U> converter) {
+    public final <U> List<U> fetch(int fieldIndex, Converter<?, ? extends U> converter) {
         return fetch().getValues(fieldIndex, converter);
     }
 
@@ -429,7 +429,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> List<U> fetch(String fieldName, Converter<?, U> converter) {
+    public final <U> List<U> fetch(String fieldName, Converter<?, ? extends U> converter) {
         return fetch().getValues(fieldName, converter);
     }
 
@@ -444,7 +444,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> List<U> fetch(Name fieldName, Converter<?, U> converter) {
+    public final <U> List<U> fetch(Name fieldName, Converter<?, ? extends U> converter) {
         return fetch().getValues(fieldName, converter);
     }
 
@@ -460,7 +460,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> U fetchOne(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U fetchOne(Field<T> field, Converter<? super T, ? extends U> converter) {
         return Convert.convert(fetchOne(field), converter);
     }
 
@@ -476,7 +476,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchOne(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U fetchOne(int fieldIndex, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchOne(fieldIndex), converter);
     }
 
@@ -492,7 +492,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchOne(String fieldName, Converter<?, U> converter) {
+    public final <U> U fetchOne(String fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchOne(fieldName), converter);
     }
 
@@ -508,7 +508,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchOne(Name fieldName, Converter<?, U> converter) {
+    public final <U> U fetchOne(Name fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchOne(fieldName), converter);
     }
 
@@ -559,7 +559,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, ? extends U> converter) {
         return Optional.ofNullable(fetchOne(field, converter));
     }
 
@@ -574,7 +574,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, ? extends U> converter) {
         return Optional.ofNullable(fetchOne(fieldIndex, converter));
     }
 
@@ -589,7 +589,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(String fieldName, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(String fieldName, Converter<?, ? extends U> converter) {
         return Optional.ofNullable(fetchOne(fieldName, converter));
     }
 
@@ -604,7 +604,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(Name fieldName, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(Name fieldName, Converter<?, ? extends U> converter) {
         return Optional.ofNullable(fetchOne(fieldName, converter));
     }
 
@@ -651,7 +651,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> U fetchAny(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U fetchAny(Field<T> field, Converter<? super T, ? extends U> converter) {
         return Convert.convert(fetchAny(field), converter);
     }
 
@@ -667,7 +667,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchAny(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U fetchAny(int fieldIndex, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchAny(fieldIndex), converter);
     }
 
@@ -683,7 +683,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchAny(String fieldName, Converter<?, U> converter) {
+    public final <U> U fetchAny(String fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchAny(fieldName), converter);
     }
 
@@ -699,7 +699,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U fetchAny(Name fieldName, Converter<?, U> converter) {
+    public final <U> U fetchAny(Name fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(fetchAny(fieldName), converter);
     }
 
@@ -1143,7 +1143,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U[] fetchArray(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(int fieldIndex, Converter<?, ? extends U> converter) {
         return fetch().intoArray(fieldIndex, converter);
     }
 
@@ -1158,7 +1158,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U[] fetchArray(String fieldName, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(String fieldName, Converter<?, ? extends U> converter) {
         return fetch().intoArray(fieldName, converter);
     }
 
@@ -1173,7 +1173,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> U[] fetchArray(Name fieldName, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(Name fieldName, Converter<?, ? extends U> converter) {
         return fetch().intoArray(fieldName, converter);
     }
 
@@ -1188,7 +1188,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> U[] fetchArray(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U[] fetchArray(Field<T> field, Converter<? super T, ? extends U> converter) {
         return fetch().intoArray(field, converter);
     }
 
@@ -1203,7 +1203,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Set<U> fetchSet(int fieldIndex, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(int fieldIndex, Converter<?, ? extends U> converter) {
         return fetch().intoSet(fieldIndex, converter);
     }
 
@@ -1218,7 +1218,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Set<U> fetchSet(String fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(String fieldName, Converter<?, ? extends U> converter) {
         return fetch().intoSet(fieldName, converter);
     }
 
@@ -1233,7 +1233,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <U> Set<U> fetchSet(Name fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(Name fieldName, Converter<?, ? extends U> converter) {
         return fetch().intoSet(fieldName, converter);
     }
 
@@ -1248,7 +1248,7 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
     }
 
     @Override
-    public final <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, ? extends U> converter) {
         return fetch().intoSet(field, converter);
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetResultSetContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetResultSetContext.java
index 3e8b1d64f9..a498b06eb2 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetResultSetContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetResultSetContext.java
@@ -87,7 +87,7 @@ class DefaultBindingGetResultSetContext<U> extends AbstractScope implements Bind
     }
 
     @Override
-    public final <T> BindingGetResultSetContext<T> convert(final Converter<T, U> converter) {
+    public final <T> BindingGetResultSetContext<T> convert(final Converter<? super T, ? extends U> converter) {
         return new DefaultBindingGetResultSetContext<T>(configuration, data, resultSet, index) {
             @Override
             public void value(T v) {
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetSQLInputContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetSQLInputContext.java
index b014ac55fa..44d3d00aef 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetSQLInputContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetSQLInputContext.java
@@ -76,7 +76,7 @@ class DefaultBindingGetSQLInputContext<U> extends AbstractScope implements Bindi
     }
 
     @Override
-    public final <T> BindingGetSQLInputContext<T> convert(final Converter<T, U> converter) {
+    public final <T> BindingGetSQLInputContext<T> convert(final Converter<? super T, ? extends U> converter) {
         return new DefaultBindingGetSQLInputContext<T>(configuration, data, input) {
             @Override
             public void value(T v) {
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetStatementContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetStatementContext.java
index cb060a6095..bf32c6dee8 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetStatementContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingGetStatementContext.java
@@ -83,7 +83,7 @@ class DefaultBindingGetStatementContext<U> extends AbstractScope implements Bind
     }
 
     @Override
-    public final <T> BindingGetStatementContext<T> convert(final Converter<T, U> converter) {
+    public final <T> BindingGetStatementContext<T> convert(final Converter<? super T, ? extends U> converter) {
         return new DefaultBindingGetStatementContext<T>(configuration, data, statement, index) {
             @Override
             public void value(T v) {
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingRegisterContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingRegisterContext.java
index ba3d717548..3100c5b6a5 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingRegisterContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingRegisterContext.java
@@ -73,7 +73,7 @@ class DefaultBindingRegisterContext<U> extends AbstractScope implements BindingR
     }
 
     @Override
-    public final <T> BindingRegisterContext<T> convert(Converter<T, U> converter) {
+    public final <T> BindingRegisterContext<T> convert(Converter<? super T, ? extends U> converter) {
         return new DefaultBindingRegisterContext<T>(configuration, data, statement, index);
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSQLContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSQLContext.java
index aee591abfc..084f68db26 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSQLContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSQLContext.java
@@ -84,7 +84,7 @@ class DefaultBindingSQLContext<U> extends AbstractScope implements BindingSQLCon
     }
 
     @Override
-    public <T> BindingSQLContext<T> convert(Converter<T, U> converter) {
+    public <T> BindingSQLContext<T> convert(Converter<? extends T, ? super U> converter) {
         return new DefaultBindingSQLContext<T>(configuration, data, render, converter.to(value), variable);
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetSQLOutputContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetSQLOutputContext.java
index 980ea11c9d..76f5ed03ee 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetSQLOutputContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetSQLOutputContext.java
@@ -73,7 +73,7 @@ class DefaultBindingSetSQLOutputContext<U> extends AbstractScope implements Bind
     }
 
     @Override
-    public final <T> BindingSetSQLOutputContext<T> convert(Converter<T, U> converter) {
+    public final <T> BindingSetSQLOutputContext<T> convert(Converter<? extends T, ? super U> converter) {
         return new DefaultBindingSetSQLOutputContext<T>(configuration, data, output, converter.to(value));
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetStatementContext.java b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetStatementContext.java
index 27ced02489..b441abe144 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetStatementContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultBindingSetStatementContext.java
@@ -80,7 +80,7 @@ class DefaultBindingSetStatementContext<U> extends AbstractScope implements Bind
     }
 
     @Override
-    public final <T> BindingSetStatementContext<T> convert(Converter<T, U> converter) {
+    public final <T> BindingSetStatementContext<T> convert(Converter<? extends T, ? super U> converter) {
         return new DefaultBindingSetStatementContext<T>(configuration, data, statement, index, converter.to(value));
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/ResultImpl.java b/jOOQ/src/main/java/org/jooq/impl/ResultImpl.java
index 13b1bfeac9..039715313a 100644
--- a/jOOQ/src/main/java/org/jooq/impl/ResultImpl.java
+++ b/jOOQ/src/main/java/org/jooq/impl/ResultImpl.java
@@ -332,7 +332,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <T, U> List<U> getValues(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> List<U> getValues(Field<T> field, Converter<? super T, ? extends U> converter) {
         return Convert.convert(getValues(field), converter);
     }
 
@@ -353,7 +353,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> List<U> getValues(int fieldIndex, Converter<?, U> converter) {
+    public final <U> List<U> getValues(int fieldIndex, Converter<?, ? extends U> converter) {
         return Convert.convert(getValues(fieldIndex), converter);
     }
 
@@ -368,7 +368,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> List<U> getValues(String fieldName, Converter<?, U> converter) {
+    public final <U> List<U> getValues(String fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(getValues(fieldName), converter);
     }
 
@@ -383,7 +383,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> List<U> getValues(Name fieldName, Converter<?, U> converter) {
+    public final <U> List<U> getValues(Name fieldName, Converter<?, ? extends U> converter) {
         return Convert.convert(getValues(fieldName), converter);
     }
 
@@ -1922,7 +1922,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> U[] intoArray(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U[] intoArray(int fieldIndex, Converter<?, ? extends U> converter) {
         return Convert.convertArray(intoArray(fieldIndex), converter);
     }
 
@@ -1939,7 +1939,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> U[] intoArray(String fieldName, Converter<?, U> converter) {
+    public final <U> U[] intoArray(String fieldName, Converter<?, ? extends U> converter) {
         return Convert.convertArray(intoArray(fieldName), converter);
     }
 
@@ -1956,7 +1956,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> U[] intoArray(Name fieldName, Converter<?, U> converter) {
+    public final <U> U[] intoArray(Name fieldName, Converter<?, ? extends U> converter) {
         return Convert.convertArray(intoArray(fieldName), converter);
     }
 
@@ -1971,7 +1971,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <T, U> U[] intoArray(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U[] intoArray(Field<T> field, Converter<? super T, ? extends U> converter) {
         return Convert.convertArray(intoArray(field), converter);
     }
 
@@ -1986,7 +1986,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> Set<U> intoSet(int fieldIndex, Converter<?, U> converter) {
+    public final <U> Set<U> intoSet(int fieldIndex, Converter<?, ? extends U> converter) {
         return new LinkedHashSet<U>(getValues(fieldIndex, converter));
     }
 
@@ -2001,7 +2001,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> Set<U> intoSet(String fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> intoSet(String fieldName, Converter<?, ? extends U> converter) {
         return new LinkedHashSet<U>(getValues(fieldName, converter));
     }
 
@@ -2016,7 +2016,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <U> Set<U> intoSet(Name fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> intoSet(Name fieldName, Converter<?, ? extends U> converter) {
         return new LinkedHashSet<U>(getValues(fieldName, converter));
     }
 
@@ -2031,7 +2031,7 @@ final class ResultImpl<R extends Record> implements Result<R>, AttachableInterna
     }
 
     @Override
-    public final <T, U> Set<U> intoSet(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> Set<U> intoSet(Field<T> field, Converter<? super T, ? extends U> converter) {
         return new LinkedHashSet<U>(getValues(field, converter));
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/impl/SelectImpl.java b/jOOQ/src/main/java/org/jooq/impl/SelectImpl.java
index 220a6aedf8..822e9014c6 100644
--- a/jOOQ/src/main/java/org/jooq/impl/SelectImpl.java
+++ b/jOOQ/src/main/java/org/jooq/impl/SelectImpl.java
@@ -2755,7 +2755,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> List<U> fetch(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> List<U> fetch(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetch(field, converter);
     }
 
@@ -2770,7 +2770,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> List<U> fetch(int fieldIndex, Converter<?, U> converter) {
+    public final <U> List<U> fetch(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetch(fieldIndex, converter);
     }
 
@@ -2785,7 +2785,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> List<U> fetch(String fieldName, Converter<?, U> converter) {
+    public final <U> List<U> fetch(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetch(fieldName, converter);
     }
 
@@ -2800,7 +2800,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> List<U> fetch(Name fieldName, Converter<?, U> converter) {
+    public final <U> List<U> fetch(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetch(fieldName, converter);
     }
 
@@ -2815,7 +2815,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> U fetchOne(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U fetchOne(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetchOne(field, converter);
     }
 
@@ -2830,7 +2830,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchOne(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U fetchOne(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOne(fieldIndex, converter);
     }
 
@@ -2845,7 +2845,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchOne(String fieldName, Converter<?, U> converter) {
+    public final <U> U fetchOne(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOne(fieldName, converter);
     }
 
@@ -2860,7 +2860,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchOne(Name fieldName, Converter<?, U> converter) {
+    public final <U> U fetchOne(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOne(fieldName, converter);
     }
 
@@ -2906,7 +2906,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> Optional<U> fetchOptional(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetchOptional(field, converter);
     }
 
@@ -2921,7 +2921,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOptional(fieldIndex, converter);
     }
 
@@ -2936,7 +2936,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(String fieldName, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOptional(fieldName, converter);
     }
 
@@ -2951,7 +2951,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Optional<U> fetchOptional(Name fieldName, Converter<?, U> converter) {
+    public final <U> Optional<U> fetchOptional(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchOptional(fieldName, converter);
     }
 
@@ -2997,7 +2997,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> U fetchAny(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U fetchAny(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetchAny(field, converter);
     }
 
@@ -3012,7 +3012,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchAny(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U fetchAny(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetchAny(fieldIndex, converter);
     }
 
@@ -3027,7 +3027,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchAny(String fieldName, Converter<?, U> converter) {
+    public final <U> U fetchAny(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchAny(fieldName, converter);
     }
 
@@ -3042,7 +3042,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U fetchAny(Name fieldName, Converter<?, U> converter) {
+    public final <U> U fetchAny(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchAny(fieldName, converter);
     }
 
@@ -3472,7 +3472,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U[] fetchArray(int fieldIndex, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetchArray(fieldIndex, converter);
     }
 
@@ -3487,7 +3487,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U[] fetchArray(String fieldName, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchArray(fieldName, converter);
     }
 
@@ -3502,7 +3502,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> U[] fetchArray(Name fieldName, Converter<?, U> converter) {
+    public final <U> U[] fetchArray(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchArray(fieldName, converter);
     }
 
@@ -3517,7 +3517,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> U[] fetchArray(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> U[] fetchArray(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetchArray(field, converter);
     }
 
@@ -3532,7 +3532,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Set<U> fetchSet(int fieldIndex, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(int fieldIndex, Converter<?, ? extends U> converter) {
         return getDelegate().fetchSet(fieldIndex, converter);
     }
 
@@ -3547,7 +3547,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Set<U> fetchSet(String fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(String fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchSet(fieldName, converter);
     }
 
@@ -3562,7 +3562,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <U> Set<U> fetchSet(Name fieldName, Converter<?, U> converter) {
+    public final <U> Set<U> fetchSet(Name fieldName, Converter<?, ? extends U> converter) {
         return getDelegate().fetchSet(fieldName, converter);
     }
 
@@ -3577,7 +3577,7 @@ final class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
     }
 
     @Override
-    public final <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, U> converter) {
+    public final <T, U> Set<U> fetchSet(Field<T> field, Converter<? super T, ? extends U> converter) {
         return getDelegate().fetchSet(field, converter);
     }
 
diff --git a/jOOQ/src/main/java/org/jooq/tools/Convert.java b/jOOQ/src/main/java/org/jooq/tools/Convert.java
index cc136de697..e5ef81e232 100644
--- a/jOOQ/src/main/java/org/jooq/tools/Convert.java
+++ b/jOOQ/src/main/java/org/jooq/tools/Convert.java
@@ -232,7 +232,7 @@ public final class Convert {
      * @throws DataTypeException - When the conversion is not possible
      */
     @SuppressWarnings("unchecked")
-    public static final <U> U[] convertArray(Object[] from, Converter<?, U> converter) throws DataTypeException {
+    public static final <U> U[] convertArray(Object[] from, Converter<?, ? extends U> converter) throws DataTypeException {
         if (from == null) {
             return null;
         }
@@ -304,15 +304,16 @@ public final class Convert {
      * @return The target type object
      * @throws DataTypeException - When the conversion is not possible
      */
-    public static final <U> U convert(Object from, Converter<?, U> converter) throws DataTypeException {
+    public static final <U> U convert(Object from, Converter<?, ? extends U> converter) throws DataTypeException {
         return convert0(from, converter);
     }
 
     /**
      * Conversion type-safety
      */
-    private static final <T, U> U convert0(Object from, Converter<T, U> converter) throws DataTypeException {
-        ConvertAll<T> all = new ConvertAll<T>(converter.fromType());
+    @SuppressWarnings("unchecked")
+    private static final <T, U> U convert0(Object from, Converter<? super T, ? extends U> converter) throws DataTypeException {
+        ConvertAll<T> all = new ConvertAll<T>((Class<T>) converter.fromType());
         return converter.from(all.from(from));
     }
 
@@ -404,15 +405,16 @@ public final class Convert {
      * @throws DataTypeException - When the conversion is not possible
      * @see #convert(Object, Converter)
      */
-    public static final <U> List<U> convert(Collection<?> collection, Converter<?, U> converter) throws DataTypeException {
+    public static final <U> List<U> convert(Collection<?> collection, Converter<?, ? extends U> converter) throws DataTypeException {
         return convert0(collection, converter);
     }
 
     /**
      * Type safe conversion
      */
-    private static final <T, U> List<U> convert0(Collection<?> collection, Converter<T, U> converter) throws DataTypeException {
-        ConvertAll<T> all = new ConvertAll<T>(converter.fromType());
+    @SuppressWarnings("unchecked")
+    private static final <T, U> List<U> convert0(Collection<?> collection, Converter<? super T, ? extends U> converter) throws DataTypeException {
+        ConvertAll<T> all = new ConvertAll<T>((Class<T>) converter.fromType());
         List<U> result = new ArrayList<U>(collection.size());
 
         for (Object o : collection) {