Revert "Use java.util.Objects instead on internal API"

This reverts commit 554a8ec9ff63c1e8dec95ecdf1e315d8f3c53ebc.

Conflicts:
	services/java/com/android/server/am/ActivityStack.java

Change-Id: I23f358d970e2d0467c6e08d82c8b665970d910e7