eZ\Publish\Core\REST\Common\FieldTypeProcessor\BaseRelationProcessor::postProcessFieldSettingsHash PHP Method

    public function postProcessFieldSettingsHash($outgoingSettingsHash)
    {
        if (isset($outgoingSettingsHash['selectionMethod'])) {
            switch ($outgoingSettingsHash['selectionMethod']) {
                case Type::SELECTION_BROWSE:
                    $outgoingSettingsHash['selectionMethod'] = 'SELECTION_BROWSE';
                    break;
                case Type::SELECTION_DROPDOWN:
                    $outgoingSettingsHash['selectionMethod'] = 'SELECTION_DROPDOWN';
            }
        }
        return $outgoingSettingsHash;
    }