REQUIRED annotation and BatchCreate

[nodirg]

We try to consistently document required fields with REQUIRED annotation and use BatchCreate pattern:

message CreateFooRequest {
  string parent = 1 [ (google.api.field_behavior) = REQUIRED ];
  Foo foo = 2 [ (google.api.field_behavior) = REQUIRED];
}

message BatchCreateFooRequest {
  string parent = 1 [ (google.api.field_behavior) = REQUIRED ];
  repeated CreateFooRequest requests = 2;
}

Here all Foos must be created in the same parent, and we allow clients to omit parent in subrequests. Marking CreateTestRequest.parent as REQUIRED seems to violate the guideline

Fields should not be described as required in order to signify ... A field which is conditionally required in some situations.

What is the recommendation in this case?

[lukesneeringer]

Oh, hmm. This is a weird situation. I think it is fine to mark it as REQUIRED in this case. I will need to figure out how to word a "subrequest exception".