As an example if there was a proto file like this:

syntax = "proto3";
package mypackage;
option java_package = "com.example";

import "google/protobuf/empty.proto";

service MyService {
  rpc Foo(google.protobuf.Empty) returns (google.protobuf.Empty) {}
}

service OtherService {
  rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty) {}
}

So lets say these two services are implemented in the same binary and when a client calls MyService.Foo internally inside my implementation of MyService.Foo I want to call OtherService.Bar to do something, is that possible? If so, how?