public void MergeFrom(WithExternalReference other)
 {
     if (other == null)
     {
         return;
     }
     if (other.value1_ != null)
     {
         if (value1_ == null)
         {
             value1_ = new global::RefByAnother();
         }
         Value1.MergeFrom(other.Value1);
     }
     if (other.Value2 != 0)
     {
         Value2 = other.Value2;
     }
     _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
 }