code: protected function applyFix(\SplFileInfo $file, Tokens $tokens)
      {
          foreach ($tokens as $index => $token) {
              if (!$token->isGivenKind(T_CONSTANT_ENCAPSED_STRING)) {
                  continue;
              }
  
              $content = $token->getContent();
              $prefix = '';
  
              if ('b' === strtolower($content[0])) {
                  $prefix = $content[0];
                  $content = substr($content, 1);
              }
  
              if (
                  '"' === $content[0] &&
                  (true === $this->configuration['strings_containing_single_quote_chars'] || false === strpos($content, "'")) &&
                  // regex: odd number of backslashes, not followed by double quote or dollar
                  !Preg::match('/(?<!\\\\)(?:\\\\{2})*\\\\(?!["$\\\\])/', $content)
              ) {
                  $content = substr($content, 1, -1);
                  $content = str_replace(['\\"', '\\$', '\''], ['"', '$', '\\\''], $content);
                  $tokens[$index] = new Token([T_CONSTANT_ENCAPSED_STRING, $prefix.'\''.$content.'\'']);
              }
          }
      }
docs: {@inheritdoc}