Looks like Map is already supported in proto2: https://developers.google.com/protocol-buffers/docs/reference/cpp-generated#map-fields
It'll greatly simply our json parsing in a few cases (e.g., converting from OCI image configuration to a protobuf definition for key->value json object): "annotations" : { "key1" : "value1", "key2" : "value2" } Previously, it's not possible to have a protobuf scheme for such a json. Thoughts? - Jie