Update WorldAnchorService.cs

server/src/Org.OpenAPITools/Services/WorldAnchorService.cs

-using System;
+//
+// ARF - Augmented Reality Framework (ETSI ISG ARF)
+//
+// Copyright 2022 ETSI
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Last change: June 2022
+//
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;