[GRPC] Handling of pointers and optional arguments
The current GRPC plugin implementation is a 'golden case' implementation that only handles structs and questionably handles pointers. It is untested what will happen for methods that take pointer types.
Implementing support for pointers is relatively straightforward:
1 For an RPC method argument, a pointer type should translate into an optional
GRPC message field.
2 In the marshall
and demarshall
code, there should be nil checking for pointer types.