doclava17: Implement missing API from RootDocImpl

Bug: 260694901
Test: ./gradlew e2eTestAOSP
Test: ./gradlew doclava17:test
Merged-In: I5f20517076aa369130f48911c7b0a4e8df94cddc
Change-Id: I5f20517076aa369130f48911c7b0a4e8df94cddc
1 file changed