Model/FormSubmission.php
public function getPayload(): ?array
    {
        return \is_string($this->payload) ? json_decode($this->payload, true) : $this->payload;
    }
public function getPayload(): ?array
    {
        return \is_string($this->payload) ? json_decode($this->payload, true) : $this->payload;
    }
TODO: simplify method once https://github.com/doctrine/doctrine2/pull/6988 is fixed.

@return array|null