private static @Nullable Optional<ComponentName> getProfileOwnerAsUser(final Context context, final int profile_id) {
		if (Hacks.DevicePolicyManager_getProfileOwnerAsUser.isAbsent()) return null;
		final DevicePolicyManager dpm = Objects.requireNonNull((DevicePolicyManager) context.getSystemService(Context.DEVICE_POLICY_SERVICE));
		try {
			return Optional.ofNullable(Hacks.DevicePolicyManager_getProfileOwnerAsUser.invoke(profile_id).on(dpm));
		} catch (final RuntimeException e) {	// IllegalArgumentException("Requested profile owner for invalid userId", re) on API 21~23
			return null;						//   or RuntimeException by RemoteException.rethrowFromSystemServer() on API 24+
		}
	}
@return the profile owner component (may not be present), or null for failure
shared/src/main/java/com/oasisfeng/island/util/DevicePolicies.java