Merge pull request #18050 from davelopez/file_sources_typings #913

Job	Run time
build-client / build-client	11m 36s
setup-selenium / setup_chromedriver	3s
Test (3.8, 0)	44m 39s
Test (3.8, 1)	54m 28s
Test (3.8, 2)	52m 18s
	2h 43m 4s

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