@Override public @Nullable String getCallingPackage() {
		final String caller = super.getCallingPackage();
		if (caller != null) return caller;
		return getCallingPackage(this);
	}
Activity with enhanced {@link #getCallingPackage()}, which detects caller even if not started by {@link #startActivityForResult(Intent, int)}.

Created by Oasis on 2019-2-27.
shared/src/main/java/com/oasisfeng/island/util/CallerAwareActivity.java