code: public function save($selectedFields = [])
      {
          $fieldsSelectedForSave = is_array($selectedFields) ? $selectedFields : func_get_args();
          $this->fieldsSelectedForSave = $fieldsSelectedForSave;
          if ($this->onBeforeSave() === false || $this->onBeforeUpdate() === false) {
              $this->fieldsSelectedForSave = [];
              return false;
          } else {
              $this->fieldsSelectedForSave = [];
          }
  
          $fields = $this->normalizeFieldsForSave($fieldsSelectedForSave);
          $resultObject = $fields === null
              ? new UpdateResult()
              : static::instantiateAdapter()->update($this->id, $fields);
          $result = $resultObject->isSuccess();
  
          $this->setEventErrorsOnFail($resultObject);
          $this->onAfterUpdate($result);
          $this->onAfterSave($result);
          $this->throwExceptionOnFail($resultObject);
  
          return $result;
      }
docs: Save model to database.
  
  @param array $selectedFields save only these fields instead of all.
  @return bool
  @throws ExceptionFromBitrix