add linked service API

Signed-off-by: Eugen Freiter <freiter@gmx.de>

Author: Eugen Freiter

src/main/java/io/github/hapjava/services/Service.java

@@ -36,4 +36,10 @@ public interface Service {
    * @return the list of linked services.
    */
   List<Service> getLinkedServices();
+
+  /**
+   * Add linked services
+   * @param service linked service
+   */
+  void addLinkedService(Service service);
 }

src/main/java/io/github/hapjava/services/impl/AbstractServiceImpl.java

@@ -9,7 +9,6 @@
 import org.slf4j.LoggerFactory;
 
 abstract class AbstractServiceImpl implements Service {
-  private final Logger logger = LoggerFactory.getLogger(this.getClass());
   private final String type;
   private final List<Characteristic> characteristics = new LinkedList<>();
   private final List<Service> linkedServices = new LinkedList<>();
@@ -38,6 +37,7 @@ public void addCharacteristic(Characteristic characteristic) {
     this.characteristics.add(characteristic);
   }
 
+  @Override
   public void addLinkedService(Service service) {
     this.linkedServices.add(service);
   }