google.api.HttpBody will contain POST body data This is based on how Envoy handles google.api.HttpBody.

google.protobuf.Any is handled specially See here for the details on the JSON mapping: https://developers.google.com/protocol-buffers/docs/proto3#json.

google.protobuf.Duration is serialized as a string.

google.protobuf.FieldMask masks is serialized as a string.

google.protobuf.Struct is equivalent to a JSON object.

google.protobuf.Timestamp is serialized as a string.

google.protobuf.Value is handled specially See here for the details on the JSON mapping: https://developers.google.com/protocol-buffers/docs/proto3#json and here: https://developers.google.com/protocol-buffers/docs/reference/google.protobuf#google.protobuf.Value.

google.rpc.Status is handled specially.

google.type.Date is serialized as a string.

google.type.DateTime is serialized as a string.