fix: grammar ambiguities from #2217

- completes #2217

Signed-off-by: Andreas Reichel <andreas@manticore-projects.com>

Author: manticore-projects

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -7860,7 +7860,7 @@ AlterExpression AlterExpression():
                 LOOKAHEAD(4)
                 (
                   ( tk=<K_SPATIAL> | tk=<K_FULLTEXT> )
-                  [ tk2=<K_INDEX> | tk2=<K_KEY> ]
+                  [ LOOKAHEAD(2) ( tk2=<K_INDEX> | tk2=<K_KEY> ) ]
                   (
                       sk3 = RelObjectName()
                       columnNames = ColumnsNamesList()
@@ -8361,15 +8361,11 @@ AlterExpression AlterExpression():
       LOOKAHEAD(2) <K_EXCHANGE> <K_PARTITION> partitions=PartitionNamesList()
         <K_WITH> <K_TABLE> tk=<S_IDENTIFIER>
         [
-          LOOKAHEAD(2) <K_WITH> <K_VALIDATION>
-          {
-            alterExp.setExchangePartitionWithValidation(true);
-          }
-        |
-          LOOKAHEAD(2) <K_WITHOUT> <K_VALIDATION>
-          {
-            alterExp.setExchangePartitionWithoutValidation(false);
-          }
+            LOOKAHEAD(2) (
+                <K_WITH> <K_VALIDATION> { alterExp.setExchangePartitionWithValidation(true); }
+                |
+                <K_WITHOUT> <K_VALIDATION> { alterExp.setExchangePartitionWithoutValidation(false); }
+            )
         ]
         {
           alterExp.setOperation(AlterOperation.EXCHANGE_PARTITION);