move UrlBookmark to its own file

@@ -4,6 +4,7 @@ Improvements:
 * The `phoneNumber` of an `SMS` is now non-null.
 * The `latitude` and `longitude` of a `GeoPoint` are now non-null.
 * The `phones` and `urls` of `ContactInfo` are now non-null.
+* The `url` of a `UrlBookmark` is now non-null.
 
 ## 3.5.0
 New Features:

@@ -21,4 +21,5 @@ export 'src/objects/email.dart';
 export 'src/objects/geo_point.dart';
 export 'src/objects/mobile_scanner_arguments.dart';
 export 'src/objects/sms.dart';
+export 'src/objects/url_bookmark.dart';
 export 'src/objects/wifi.dart';

@@ -2,7 +2,6 @@ import 'dart:math' as math;
 
 import 'package:flutter/material.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
-import 'package:mobile_scanner/src/objects/geo_point.dart';
 
 Size toSize(Map data) {
   final width = data['width'] as double;

@@ -12,6 +12,7 @@ import 'package:mobile_scanner/src/objects/driver_license.dart';
 import 'package:mobile_scanner/src/objects/email.dart';
 import 'package:mobile_scanner/src/objects/geo_point.dart';
 import 'package:mobile_scanner/src/objects/sms.dart';
+import 'package:mobile_scanner/src/objects/url_bookmark.dart';
 import 'package:mobile_scanner/src/objects/wifi.dart';
 
 /// Represents a single recognized barcode and its value.
@@ -206,21 +207,3 @@ class Phone {
       : number = data['number'] as String?,
         type = PhoneType.values[data['type'] as int];
 }
-
-/// A URL and title from a 'MEBKM:' or similar QRCode type.
-class UrlBookmark {
-  /// Gets the title of the bookmark.
-  ///
-  /// Returns null if not available.
-  final String? title;
-
-  /// Gets the url of the bookmark.
-  ///
-  /// Returns null if not available.
-  final String? url;
-
-  /// Create a [UrlBookmark] from native data.
-  UrlBookmark.fromNative(Map data)
-      : title = data['title'] as String?,
-        url = data['url'] as String?;
-}

+/// A URL and title from a `MEBKM:` or similar QRCode type.
+class UrlBookmark {
+  /// Construct a new [UrlBookmark] instance.
+  const UrlBookmark({
+    this.title,
+    required this.url,
+  });
+
+  /// Construct a new [UrlBookmark] instance from the given [data].
+  factory UrlBookmark.fromNative(Map<Object?, Object?> data) {
+    return UrlBookmark(
+      title: data['title'] as String?,
+      url: data['url'] as String? ?? '',
+    );
+  }
+
+  /// The title of the bookmark.
+  final String? title;
+
+  /// The url of the bookmark.
+  final String url;
+}