@RequiresPermission(Permissions.INTERACT_ACROSS_USERS) public static boolean enableFileShuttle(final Activity activity) {
		if (Modules.getFileProviderComponent(activity) == null) {
			Toast.makeText(activity, "Module \"File Provider\" not installed.", Toast.LENGTH_LONG).show();
			return false;
		}
		Analytics.$().event("file_shuttle_request").send();
		if (Permissions.has(activity, WRITE_EXTERNAL_STORAGE)) {
			onPermissionGranted(activity);
			return true;
		}
		com.oasisfeng.android.content.pm.Permissions.request(activity, WRITE_EXTERNAL_STORAGE, result -> {
			if (result == PERMISSION_GRANTED) onPermissionGranted(activity);
			else Toast.makeText(activity, R.string.toast_external_storage_permission_required, Toast.LENGTH_LONG).show();
		});
		return false;
	}
@return true if activated synchronously, false for failure or asynchronous procedure.
mobile/src/main/java/com/oasisfeng/island/files/IslandFiles.java