code: protected function createConfigurationDefinition()
      {
          $sets = ['@internal', '@IMAP', '@mbreg', '@all'];
  
          return new FixerConfigurationResolver([
              (new FixerOptionBuilder('sets', 'List of sets to fix. Defined sets are `@internal` (native functions), `@IMAP` (IMAP functions), `@mbreg` (from `ext-mbstring`) `@all` (all listed sets).'))
                  ->setAllowedTypes(['array'])
                  ->setAllowedValues([new AllowedValueSubset($sets)])
                  ->setDefault(['@internal', '@IMAP'])
                  ->getOption(),
          ]);
      }
docs: {@inheritdoc}