code: public static <ContainingType extends MessageLite, Type>
        GeneratedExtension<ContainingType, Type>
            newRepeatedGeneratedExtension(
                final ContainingType containingTypeDefaultInstance,
                final MessageLite messageDefaultInstance,
                final Internal.EnumLiteMap<?> enumTypeMap,
                final int number,
                final WireFormat.FieldType type,
                final boolean isPacked) {
      @SuppressWarnings("unchecked")  // Subclasses ensure Type is a List
      Type emptyList = (Type) Collections.emptyList();
      return new GeneratedExtension<ContainingType, Type>(
          containingTypeDefaultInstance,
          emptyList,
          messageDefaultInstance,
          new ExtensionDescriptor(
              enumTypeMap, number, type, true /* isRepeated */, isPacked));
    }
docs: For use by generated code only.