Utility/Fields/FieldBase.php
public function saveField()
    {
        $entity = Entity::getEntity($this->entityId, $this->entityType, $this->fieldId);
        if (!$entity->id) {
            $entity->entity_id = $this->entityId;
            $entity->field_id = $this->fieldId;
            $entity->entity_type = $this->entityType;
            $entity->save();
        }
        $this->model->entity_field_id = $entity->id;
        $this->model->locale = $this->locale;
        $this->model->value = $this->getValue();
        $this->model->save();
    }
public function saveField()
    {
        $entity = Entity::getEntity($this->entityId, $this->entityType, $this->fieldId);
        if (!$entity->id) {
            $entity->entity_id = $this->entityId;
            $entity->field_id = $this->fieldId;
            $entity->entity_type = $this->entityType;
            $entity->save();
        }
        $this->model->entity_field_id = $entity->id;
        $this->model->locale = $this->locale;
        $this->model->value = $this->getValue();
        $this->model->save();
    }
Save normal field.