Update stats-log-api-gen source based off of google3 presubmit checks

Bug: 161812407
Test: `m statslog-framework-java-gen`
Test: `m statslog-telephony-java-gen`
Test: `m stats-log-api-gen-test && out/host/linux-x86/nativetest/stats-log-api-gen-test/stats-log-api-gen-test`
Change-Id: Id68982e306fbc379ed8e90b33a38b8a6604e66ad