public function processField2Filter(Builder $builder, Constraint $constraint)
 {
     if ($constraint->getOperator() == Constraint::OPERATOR_IN && is_array($constraint->getValue()) && $constraint->getValue()) {
         $builder->where('field2', $constraint->getValue()[0]);
         return true;
     }
 }
 public function processRelationA_FieldFilter(Builder $builder, Constraint $constraint)
 {
     $builder->where('relation_a_field', $constraint->getValue());
     return true;
 }