code: func Message(out proto.Message) interface {
  	cfgclient.Resolver
  	cfgclient.FormattingResolver
  } {
  	if out == nil {
  		panic("cannot pass a nil proto.Message instance")
  	}
  	return &resolver{
  		messageName: proto.MessageName(out),
  		single:      out,
  		singleType:  reflect.TypeOf(out),
  	}
  }
docs: // Message is a cfgclient.Resolver that resolves config data into proto.Message
  // instances by parsing the config data as a text protobuf.