Match return types for addFirst and addLast with List am: 9b651e268b am: 1f6c204bb8

Original change: https://android-review.googlesource.com/c/platform/external/javaparser/+/2887806

Change-Id: Ifd8c87a61a4e89120d1a2847c03b0d249be84997
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>