Fix errorprone warnings that should be errors am: a8f72f0e21 am: e5a326cd96 am: ad71dcb9c7

Original change: https://android-review.googlesource.com/c/platform/external/nanohttpd/+/2254824

Change-Id: I160814456368be0e84743f365eee04f1e5d7953f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>