code: protected function createConfigurationDefinition()
      {
          $functionNames = array_keys(self::$availableFunctions);
  
          return new FixerConfigurationResolver([
              (new FixerOptionBuilder('functions', 'List of function names to fix.'))
                  ->setAllowedTypes(['array'])
                  ->setAllowedValues([new AllowedValueSubset($functionNames)])
                  ->setDefault([
                      'get_class',
                      'php_sapi_name',
                      'phpversion',
                      'pi',
                      // TODO on v3.0 add 'get_called_class' here
                  ])
                  ->getOption(),
          ]);
      }
docs: {@inheritdoc}