Fix join issue

Signed-off-by: Tomoyuki Morita <[email protected]>

Author: ykmr1224

core/src/main/java/org/opensearch/sql/calcite/rel/RelFieldBuilder.java

@@ -170,6 +170,10 @@ public void reorganizeDynamicFields(List<String> leftAllFields, List<String> rig
     boolean leftHasDynamicFields = leftAllFields.contains(DYNAMIC_FIELDS_MAP);
     boolean rightHasDynamicFields = rightAllFields.contains(DYNAMIC_FIELDS_MAP);
 
+    if (!leftHasDynamicFields && !rightHasDynamicFields) {
+      return;
+    }
+
     List<JoinedField> fields = collectStaticFieldsInfo(leftAllFields, rightAllFields);
     Optional<JoinedField> leftMap =
         leftHasDynamicFields ? Optional.of(getLeftDynamicFieldMapInfo()) : Optional.empty();