Update methods: Mask field expected behavior

This rule enforces that the update_mask field of a Standard Update request uses google.api.field_behavior = OPTIONAL, as mandated in AIP-134.

Details

This rule looks at any field named update_mask that’s in an Update*Request and complains if the field is not annotated with google.api.field_behavior = OPTIONAL.

Examples

Incorrect code for this rule:

message UpdateBookRequest {
  Book book = 1;

  // Incorrect. Must be `OPTIONAL`.
  google.protobuf.FieldMask update_mask = 2 [  
    (google.api.field_behavior) = REQUIRED
  ];
}

Correct code for this rule:

message UpdateBookRequest {
  Book book = 1;

  // Correct.
  google.protobuf.FieldMask update_mask = 2 [
    (google.api.field_behavior) = OPTIONAL
  ];
}

Disabling

If you need to violate this rule, use a leading comment above the message. Remember to also include an aip.dev/not-precedent comment explaining why.

message UpdateBookRequest {
  Book book = 1;

  // (-- api-linter: core::0134::update-mask-optional-behavior=disabled
  //     aip.dev/not-precedent: We need to do this because reasons. --)
  google.protobuf.FieldMask update_mask = 2 [  
    (google.api.field_behavior) = REQUIRED
  ];
}

If you need to violate this rule for an entire file, place the comment at the top of the file.