GetArenaNoVirtual is returning no Arena even after creating the message using Arena

[LakshmiKanth Gupta]

message MyRec1

{

  int32 a=1;

}

message MyRec

{

   MyRec1 rec = 1;

}

auto *rec= google::protobuf::Arena::Create<MyRec>(arena);

rec->mutable_rec()->set_a(100);

mtable_rec() is creating memory using new...Arena which I have used for creating MyRec is not used.

Please help.