Disabling some "unused" warnings

I'd submitted code that's never actually used in the android/snippets apps. Ideally we'd include it in an app, but in the meantime, disabling the "unused" warnings.

Also removed one line (outside of a published-on-DAC code block) that turned out not to be needed.

No changes to the code that's included on DAC, and the code still compiles.

(I also see some areas where the actual code snippet is generating warnings, but I'll resolve those in separate PRs that can be reviewed by the appropriate SMEs for those docs.)

Author: asolovay

misc/src/main/java/com/example/snippets/backgroundwork/WakeLockSnippetsJava.java

@@ -6,7 +6,7 @@
 
 import androidx.annotation.Nullable;
 
-@SuppressWarnings("Unused")
+@SuppressWarnings("UNUSED")
 public class WakeLockSnippetsJava extends Activity {
 
     PowerManager.WakeLock wakeLock;