What version of protobuf and what language are you using?
Version: 3.6.1
Language: Ruby

What operating system (Linux, Windows, ...) and version?
MacOS 10.14

What runtime / compiler are you using (e.g., python version or gcc version)
Ruby 2.4.1

What did you do?
Steps to reproduce the behavior:

1. Compile the following proto: protoc --proto_path=. --ruby_out=. example.proto

syntax = "proto3";

package google.example;

option java_multiple_files = true;
//option ruby_package = "Google::Example";

service HelloService {
     rpc HiThere (HiRequest) returns (HiResponse);
}

message HiRequest {
    string query = 1;
}

message HiResponse {
    string result = 1;
}

2. Repeat step 1 after uncommenting the ruby_package line.

What did you expect to see
The generated Ruby code should be the same.

What did you see instead?
When the ruby_package options is specified the generated code is:

module Google::Example
  HiRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("google.example.HiRequest").msgclass
  HiResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("google.example.HiResponse").msgclass
end

Without the ruby_package option it is:

module Google
  module Example
    HiRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("google.example.HiRequest").msgclass
    HiResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("google.example.HiResponse").msgclass
  end
end

This inconsistency causes issues because the module must already be defined if the ruby_package option is used (example: googleapis/google-cloud-ruby#2782).

Anything else we should know about your project / environment