nextcloud: Support setting last modified time when uploading

packages/nextcloud/lib/src/webdav/client.dart

@@ -175,19 +175,31 @@ class WebDavClient {
       );
 
   /// upload a new file with [localData] as content to [remotePath]
-  Future<HttpClientResponse> upload(final Uint8List localData, final String remotePath) => _send(
+  Future<HttpClientResponse> upload(
+    final Uint8List localData,
+    final String remotePath, {
+    final DateTime? lastModified,
+  }) =>
+      _send(
         'PUT',
         _constructPath(remotePath),
         [200, 201, 204],
         data: Stream.value(localData),
+        headers: lastModified != null ? {'X-OC-Mtime': (lastModified.millisecondsSinceEpoch ~/ 1000).toString()} : null,
       );
 
   /// upload a new file with [localData] as content to [remotePath]
-  Future<HttpClientResponse> uploadStream(final Stream<Uint8List> localData, final String remotePath) async => _send(
+  Future<HttpClientResponse> uploadStream(
+    final Stream<Uint8List> localData,
+    final String remotePath, {
+    final DateTime? lastModified,
+  }) async =>
+      _send(
         'PUT',
         _constructPath(remotePath),
         [200, 201, 204],
         data: localData,
+        headers: lastModified != null ? {'X-OC-Mtime': (lastModified.millisecondsSinceEpoch ~/ 1000).toString()} : null,
       );
 
   /// download [remotePath] and store the response file contents to String

packages/nextcloud/test/webdav.dart

@@ -89,6 +89,27 @@ Future run(final DockerImage image) async {
       expect(txtFile.size, txtBytes.lengthInBytes);
     });
 
+    test('Upload file with modified time', () async {
+      final lastModified = DateTime.fromMillisecondsSinceEpoch(DateTime.now().millisecondsSinceEpoch ~/ 1000 * 1000);
+      final txtBytes = File('test/files/test.txt').readAsBytesSync();
+
+      final response = await client.webdav.upload(
+        txtBytes,
+        'test.txt',
+        lastModified: lastModified,
+      );
+      expect(response.statusCode, equals(201));
+
+      final files = await client.webdav.ls(
+        '/',
+        props: {
+          WebDavProps.davLastModified.name,
+        },
+      );
+      final txtFile = files.singleWhere((final f) => f.name == 'test.txt');
+      expect(txtFile.lastModified!.millisecondsSinceEpoch, lastModified.millisecondsSinceEpoch);
+    });
+
     test('Copy file', () async {
       final response = await client.webdav.copy(
         'Nextcloud.png',