Add null guard for AddCommentToMethod and NumberToDuration #3131

Job	Run time
check-s3-related-changes	1m 5s
s3-regression-tests-upload-crt	2m 21s
s3-regression-tests-upload-async	2m 21s
s3-regression-tests-upload-sync	2m 22s
s3-regression-tests-control-plane	2m 20s
s3-regression-tests-upload-multi	2m 22s
s3-regression-tests-download	2m 22s
	15m 13s

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