tests/regression/issue_524/oneof.proto

syntax = "proto3";

import "submessage.proto";

package mymessage;

message MyMessage
{
    oneof foo
    {
        submessage.SubMessage1 msg1 = 1;
        submessage.SubMessage2 msg2 = 2;
        submessage.SubMessage3 msg3 = 3;
    }
}