class ErrorResponsePart implements ResponsePartInterface
{
   /**
    * Specification.
    *
    * @var SpecificationInterface $specification
    */
   private $specification;

   /**
    * Response part data.
    *
    * @var ResponseDtoInterface $partData
    */
   private $partData;

   /**
    * Formatter context.
    *
    * @var FormatterContext $formatterContext
    */
   private $formatterContext;

   /**
    * ErrorResponsePart constructor.
    *
    * @param SpecificationInterface $specification
    * @param FormatterContext $formatterContext
    */
   public function __construct(SpecificationInterface $specification, FormatterContext $formatterContext)
   {
       $this->specification = $specification;
       $this->formatterContext = $formatterContext;
   }

   /**
    * {@inheritdoc}
    */
   public function addData(ResponseDtoInterface $data) : void
   {
       if ($this->specification->isSatisfiedBy($data)) {
           $this->partData = $this->formatterContext->process($data);
       }
   }
}