add addLabel

- add class LabelPrototype

wrapper/src/main/java/wekan/wrapper/api/BoardService.java

@@ -3,6 +3,7 @@ package wekan.wrapper.api;
 import retrofit2.Call;
 import retrofit2.http.*;
 import wekan.wrapper.entity.Board;
+import wekan.wrapper.entity.LabelPrototype;
 import wekan.wrapper.entity.MemberPermission;
 import wekan.wrapper.entity.BoardPrototype;
 
@@ -21,6 +22,12 @@ public interface BoardService {
     @DELETE("api/boards/{boardId}")
     Call<Void> deleteBoard(@Path("boardId") String boardId);
 
+    @PUT("/api/boards/{boardId}/labels")
+    Call<String> addLabel(
+            @Path("boardId") String board,
+            @Body LabelPrototype labelPrototype
+    );
+
     @POST("/api/boards/{boardId}/members/{memberId}")
     Call<Void> setMemberPermission(
             @Path("boardId") String board,

wrapper/src/main/java/wekan/wrapper/entity/LabelPrototype.java

@@ -0,0 +1,9 @@
+package wekan.wrapper.entity;
+
+public class LabelPrototype {
+    private Label label;
+
+    public LabelPrototype(String name, LabelColor color) {
+        label = new Label(null, name, color);
+    }
+}