code: protected function getParameterSignatures($method)
      {
          $signatures = [];
          $parameters = $method->getParameters();
          foreach ($parameters as $parameter) {
              $signature = '';
              $signature .= $this->getParameterTypeHint($parameter);
              if ($parameter->isPassedByReference()) {
                  $signature .= '&';
              }
              // Guard: Variadic methods only supported by PHP 5.6+
              $isVariadic = (PHP_VERSION_ID >= 50600) && $parameter->isVariadic();
              if ($isVariadic) {
                  $signature .= '...';
              }
              $signature .= '$' . $parameter->getName();
              if (!$isVariadic) {
                  if ($parameter->isDefaultValueAvailable()) {
                      $signature .= ' = ' . var_export($parameter->getDefaultValue(), true);
                  } elseif ($parameter->isOptional()) {
                      $signature .= ' = null';
                  }
              }
  
              $signatures[] = $signature;
          }
  
          return implode(', ', $signatures);
      }
docs: Get the source code for the parameters of a method.
  
  @param ReflectionMethod $method   Method object from reflection API
  
  @return string The Parameters string for a method.