code: func (f FileInfo) GoPluginOutputFilename() string {
  	name := f.Name
  	ext := path.Ext(name)
  	if ext == ".proto" || ext == ".protodevel" {
  		name = name[0 : len(name)-len(ext)]
  	}
  	return name + ".pb.go"
  }
docs: // GoPluginOutputFilename returns the filename the vanilla go protoc
  // plugin will use when generating output for this file.