expose IssueLabel.description; update labels REST APIs (#355)

* expose IssueLabel.description; update labels REST APIs

* add a deprecated forwarding method

* Update issues_service.dart

---------

Co-authored-by: Rob Becker <robrbecker@gmail.com>

lib/src/common/issues_service.dart

@@ -290,19 +290,49 @@ class IssuesService extends Service {
   ///
   /// API docs: https://developer.github.com/v3/issues/labels/#create-a-label
   Future<IssueLabel> createLabel(
-      RepositorySlug slug, String name, String color) {
-    return github.postJSON('/repos/${slug.fullName}/labels',
-        body: GitHubJson.encode({'name': name, 'color': color}),
-        convert: IssueLabel.fromJson);
+    RepositorySlug slug,
+    String name, {
+    String? color,
+    String? description,
+  }) {
+    return github.postJSON(
+      '/repos/${slug.fullName}/labels',
+      body: GitHubJson.encode({
+        'name': name,
+        if (color != null) 'color': color,
+        if (description != null) 'description': description,
+      }),
+      convert: IssueLabel.fromJson,
+    );
   }
 
   /// Edits a label.
   ///
   /// API docs: https://developer.github.com/v3/issues/labels/#update-a-label
+  @Deprecated('See updateLabel instead.')
   Future<IssueLabel> editLabel(RepositorySlug slug, String name, String color) {
-    return github.postJSON('/repos/${slug.fullName}/labels/$name',
-        body: GitHubJson.encode({'name': name, 'color': color}),
-        convert: IssueLabel.fromJson);
+    return updateLabel(slug, name, color: color);
+  }
+
+  /// Update a label.
+  ///
+  /// API docs: https://developer.github.com/v3/issues/labels/#update-a-label
+  Future<IssueLabel> updateLabel(
+    RepositorySlug slug,
+    String name, {
+    String? newName,
+    String? color,
+    String? description,
+  }) {
+    return github.patchJSON(
+      '/repos/${slug.fullName}/labels/$name',
+      body: GitHubJson.encode({
+        if (newName != null) 'new_name': newName,
+        if (color != null) 'color': color,
+        if (description != null) 'description': description,
+      }),
+      convert: IssueLabel.fromJson,
+    );
   }
 
   /// Deletes a label.

lib/src/common/model/issues.dart

@@ -172,12 +172,15 @@ class IssueLabel {
   IssueLabel({
     this.name = '',
     this.color = '',
+    this.description = '',
   });
 
   String name;
 
   String color;
 
+  String description;
+
   factory IssueLabel.fromJson(Map<String, dynamic> input) =>
       _$IssueLabelFromJson(input);
   Map<String, dynamic> toJson() => _$IssueLabelToJson(this);