src/Codec/Codec.php
public function document($request): ?\stdClass
    {
        if ($this->cannotDecodeJsonApi()) {
            return null;
        }

        return $this->decoding->getJsonApiDecoder()->document($request);
    }
public function document($request): ?\stdClass
    {
        if ($this->cannotDecodeJsonApi()) {
            return null;
        }

        return $this->decoding->getJsonApiDecoder()->document($request);
    }
Decode a JSON API document from the request content.

@param $request
@return \stdClass|null