Fix source-generator infinite loop #432

Job	Run time
build (windows-latest, net472, 20.x, Release)	8m 21s
build (windows-latest, net6.0, 20.x, Release)	7m 36s
build (windows-latest, net8.0, 18.x, Release)	8m 49s
build (windows-latest, net8.0, 20.x, Release)	8m 48s
build (macos-latest, net6.0, 20.x, Release)	2m 35s
build (macos-latest, net8.0, 18.x, Release)	3m 44s
build (macos-latest, net8.0, 20.x, Release)	3m 45s
build (ubuntu-latest, net6.0, 20.x, Release)	3m 48s
build (ubuntu-latest, net8.0, 18.x, Release)	5m 21s
build (ubuntu-latest, net8.0, 20.x, Release)	5m 25s
	58m 12s

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