public function find($id, bool $getRelations = null): ? Entity
    {
        if (! \is_string($id) && ! \is_int($id)) {
            throw new InvalidArgumentException('ID should be an int or string only.');
        }

        return $this->findBy(
                [$this->entity::getIdField() => $id],
                null,
                null,
                null,
                null,
                $getRelations
            )[0]
            ?? null;
    }