Make sure webhook messages can be versionised later.

app/Generator/Webhook/MessageGeneratorInterface.php

@@ -0,0 +1,57 @@
+<?php
+/*
+ * MessageGeneratorInterface.php
+ * Copyright (c) 2020 james@firefly-iii.org
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace FireflyIII\Generator\Webhook;
+
+use FireflyIII\User;
+use Illuminate\Support\Collection;
+
+/**
+ * Interface MessageGeneratorInterface
+ */
+interface MessageGeneratorInterface
+{
+
+    /**
+     * @return int
+     */
+    public function getVersion(): int;
+
+    /**
+     *
+     */
+    public function generateMessages(): void;
+
+    /**
+     * @param User $user
+     */
+    public function setUser(User $user): void;
+
+    /**
+     * @param Collection $transactionGroups
+     */
+    public function setTransactionGroups(Collection $transactionGroups): void;
+
+    /**
+     * @param int $trigger
+     */
+    public function setTrigger(int $trigger): void;
+}