Proto2 mandates that required fields always appear in the serialized output, even when they match the default value. Not doing so will cause an error when interoperating with other implementations.
Duplicate of #68, which was fixed with 717ae6931523e239ac68ee8fa4cb6b8d6c5fb6d4.
(I had uncommitted files on one of my dev boxes, causing some confusion. These were already committed from a different PC.)
Proto2 mandates that required fields always appear in the serialized output, even when they match the default value. Not doing so will cause an error when interoperating with other implementations.