docs: private void checkEnumTypeExtensions(List<GraphQLError> errors, TypeDefinitionRegistry typeRegistry) {
          typeRegistry.enumTypeExtensions()
                  .forEach((name, extensions) -> {
                      checkTypeExtensionHasCorrespondingType(errors, typeRegistry, name, extensions, EnumTypeDefinition.class);
                      checkTypeExtensionDirectiveRedefinition(errors, typeRegistry, name, extensions, EnumTypeDefinition.class);
  
                      extensions.forEach(extension -> {
                          // field unique ness
                          List<EnumValueDefinition> enumValueDefinitions = extension.getEnumValueDefinitions();
                          checkNamedUniqueness(errors, enumValueDefinitions, EnumValueDefinition::getName,
                                  (namedField, enumValue) -> new NonUniqueNameError(extension, enumValue));
  
                          //
                          // enum values must be unique within a type extension
                          forEachBut(extension, extensions,
                                  otherTypeExt -> checkForEnumValueRedefinition(errors, otherTypeExt, otherTypeExt.getEnumValueDefinitions(), enumValueDefinitions));
  
                          //
                          // then check for field re-defs from the base type
                          Optional<EnumTypeDefinition> baseTypeOpt = typeRegistry.getType(extension.getName(), EnumTypeDefinition.class);
                          baseTypeOpt.ifPresent(baseTypeDef -> checkForEnumValueRedefinition(errors, extension, enumValueDefinitions, baseTypeDef.getEnumValueDefinitions()));
  
                      });
  
  
                  });
      }