walt: app: fix Lint errors of java in the main folder am: cab1e13775 am: 2f3c46b1be am: 65205d9e64 am: 03512a1890 am: 83c4ec84bf am: 19a6b70865

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/walt/+/11895599

Change-Id: I5a2a4163fa4c4355d7ac9c4f877bf93b5d848dfe