am ddf77b19: am b22123d1: am e41d4c04: am 0ea68954: am a5273888: am 538abc5b: am d6aeae14: Merge "Don\'t serialize required fields whose \'has\' flags are unset."

* commit 'ddf77b1914d3f2b0bd1310cedc41713fe7d2fbe4':