@Override
 public ActionRequestValidationException validate() {
   ActionRequestValidationException validationException = super.validate();
   if (type == null) {
     validationException =
         ValidateActions.addValidationError("type is missing", validationException);
   }
   if (id == null && doc == null) {
     validationException =
         ValidateActions.addValidationError("id or doc is missing", validationException);
   }
   return validationException;
 }
 @Override
 public ActionRequestValidationException validate() {
   ActionRequestValidationException validationException = null;
   if (index == null) {
     validationException =
         ValidateActions.addValidationError("index is missing", validationException);
   }
   return validationException;
 }
 @Override
 public ActionRequestValidationException validate() {
   ActionRequestValidationException validationException = null;
   if (items.isEmpty()) {
     validationException =
         ValidateActions.addValidationError("no documents to get", validationException);
   } else {
     for (int i = 0; i < items.size(); i++) {
       Item item = items.get(i);
       if (item.index() == null) {
         validationException =
             ValidateActions.addValidationError(
                 "index is missing for doc " + i, validationException);
       }
       if (item.id() == null) {
         validationException =
             ValidateActions.addValidationError("id is missing for doc " + i, validationException);
       }
     }
   }
   return validationException;
 }