[#7749] Support parsing CREATE INDEX .. ON .. USING btree (..)

jOOQ-manual/src/main/resources/org/jooq/web/grammar-3.12.txt

@@ -122,7 +122,7 @@ break
 ;
 
 createIndexStatement = 'CREATE' [ 'UNIQUE' ] 'INDEX' [ 'IF NOT EXISTS' ] [ indexName ] break
-  'ON' tableName '(' sortFields ')'
+  'ON' tableName [ 'USING' 'BTREE' ] '(' sortFields ')'
   [ 'INCLUDE' '(' identifiers ')' ]
   [ 'WHERE' condition ]
 ;

jOOQ/src/main/java/org/jooq/impl/ParserImpl.java

@@ -3269,6 +3269,7 @@ final class ParserImpl implements Parser {
         Name indexName = parseIndexNameIf(ctx);
         parseKeyword(ctx, "ON");
         Table<?> tableName = parseTableName(ctx);
+        parseKeywordIf(ctx, "USING BTREE");
         parse(ctx, '(');
         SortField<?>[] fields = parseSortSpecification(ctx).toArray(EMPTY_SORTFIELD);
         parse(ctx, ')');