Original thread #261 (comment) (is a PR)

If we have a field whose type is a map with Timestamp as its value type, and the stdtime is used in that field, then the imports are broken because...

1. GoMapType gets called with the FieldDescriptorProto of the field itself.
2. In GoMapType, GoType is called for both the key and value types but...
3. Protobuf have no notion of types, but of fields, and therefore, bot the key and value types fields are not aware of the options in the map type field.