[FSSDK-11638] cleanups in event processing (#1073) #1276

Job	Run time
lint	1m 27s
unit_tests (18)	2m 3s
unit_tests (24)	1m 42s
unit_tests (20)	1m 52s
lint_markdown_files / lint	1m 17s
integration_tests / test	9s
unit_tests (22)	1m 59s
fullstack_production_suite / test	7s
Coveralls coverage	5s
	10m 41s

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