Convert all content types to string #842

Job	Run time
unit-tests (ubuntu-latest, nightly)	1m 53s
unit-tests (macos-latest, v0.11.1)	59s
unit-tests (ubuntu-latest, v0.11.1)	1m 7s
unit-tests (windows-latest, nightly)	1m 45s
unit-tests (windows-latest, v0.11.1)	1m 28s
unit-tests (macos-latest, nightly)	57s
	8m 9s

Provide feedback