diff --git a/lib/public/Files_FullTextSearch/Model/AFilesDocument.php b/lib/public/Files_FullTextSearch/Model/AFilesDocument.php
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+<?php
+declare(strict_types=1);
+
+
+/**
+ * Files_FullTextSearch - Index the content of your files
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later. See the COPYING file.
+ *
+ * @author Maxence Lange <maxence@artificial-owl.com>
+ * @copyright 2018
+ * @license GNU AGPL version 3 or any later version
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+namespace OCP\Files_FullTextSearch\Model;
+
+
+use OCP\FullTextSearch\Model\IndexDocument;
+
+
+/**
+ * Abstract Class AFilesDocument
+ *
+ * This is mostly used by 3rd party apps that want to complete the IndexDocument
+ * with more information about a file before its index:
+ *
+ *    \OC::$server->getEventDispatcher()->addListener(
+ *        '\OCA\Files_FullTextSearch::onFileIndexing',
+ *        function(GenericEvent $e) {
+ *            //@var \OCP\Files\Node $file
+ *            $file = $e->getArgument('file');
+ *
+ *            // @var \OCP\Files_FullTextSearch\Model\AFilesDocument $document
+ *            $document = $e->getArgument('document');
+ *
+ *        }
+ *    );
+ *
+ * @since 15.0.0
+ *
+ * @package OCP\Files_FullTextSearch\Model
+ */
+abstract class AFilesDocument extends IndexDocument {
+
+
+	/**
+	 * Returns the owner of the document/file.
+	 *
+	 * @since 15.0.0
+	 *
+	 * @return string
+	 */
+	abstract public function getOwnerId(): string;
+
+
+	/**
+	 * Returns the current viewer of the document/file.
+	 *
+	 * @since 15.0.0
+	 *
+	 * @return string
+	 */
+	abstract public function getViewerId(): string;
+
+
+	/**
+	 * Returns the type of the document/file.
+	 *
+	 * @since 15.0.0
+	 *
+	 * @return string \OCP\Files\FileInfo::TYPE_FILE|\OCP\Files\FileInfo::TYPE_FOLDER
+	 */
+	abstract public function getType(): string;
+
+
+	/**
+	 * Returns the mimetype of the document/file.
+	 *
+	 * @since 15.0.0
+	 *
+	 * @return string
+	 */
+	abstract public function getMimetype(): string;
+
+	/**
+	 * Returns the path of the document/file.
+	 *
+	 * @since 15.0.0
+	 *
+	 * @return string
+	 */
+	abstract public function getPath(): string;
+
+
+}
+