src/Entity/Organization.php
public function isEmployee(UserInterface $user)
    {
        return $this->refs && in_array($user->getId(), $this->refs->getEmployeeIds());
    }
public function isEmployee(UserInterface $user)
    {
        return $this->refs && in_array($user->getId(), $this->refs->getEmployeeIds());
    }
Returns true, if a User is an employee of the organization

@param UserInterface $user

@return bool