Merge "Handle @sdkExtSince" am: 4775cbbc60

Original change: https://android-review.googlesource.com/c/platform/external/doclava/+/2214834

Change-Id: Iaf609633d417eea06f430ce13916b9cadac3ff0b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>