feat: use default interface methods in interceptors

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/CollectionCreateHandler.java

@@ -16,7 +16,9 @@
  */
 public interface CollectionCreateHandler {
 
-    void beforeCreateCollection(CollectionItem collection);
+    default void beforeCreateCollection(CollectionItem collection) {
+    }
 
-    void afterCreateCollection(CollectionItem collection);
+    default void afterCreateCollection(CollectionItem collection) {
+    }
 }

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/CollectionDeleteHandler.java

@@ -18,9 +18,12 @@ public interface CollectionDeleteHandler {
     /**
      * This method contains the code inserted before a collection is deleted.
      */
-    public void beforeDeleteCollection(String calendarName);
+    default void beforeDeleteCollection(String calendarName) {
+    }
+
     /**
      * This method contains the code inserted after a collection is deleted.
      */
-    public void afterDeleteCollection(String calendarName);
+    default void afterDeleteCollection(String calendarName) {
+    }
 }

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/CollectionUpdateHandler.java

@@ -22,6 +22,6 @@ public interface CollectionUpdateHandler {
      * This method contains the code inserted before a collection is updated..
      * @param collection 
      */
-    public void beforeUpdateCollection(CollectionItem collection);
+    void beforeUpdateCollection(CollectionItem collection);
 
 }

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/EventAddHandler.java

@@ -25,14 +25,16 @@ public interface EventAddHandler {
      * @param parent CollectionItem
      * @param contentItems Set<ContentItem>
      */
-    public void beforeAdd(CollectionItem parent, Set<ContentItem> contentItems);
+    default void beforeAdd(CollectionItem parent, Set<ContentItem> contentItems) {
+    }
 
     /**
      * This method contains the code inserted after an event to be added.
      * 
      * @param parent CollectionItem
      * @param contentItems Set<ContentItem>
      */
-    public void afterAdd(CollectionItem parent, Set<ContentItem> contentItems);
+    default void afterAdd(CollectionItem parent, Set<ContentItem> contentItems) {
+    }
 
 }

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/EventRemoveHandler.java

@@ -25,13 +25,15 @@ public interface EventRemoveHandler {
      * @param parent CollectionItem
      * @param items Set<Item> to remove
      */
-    public void beforeRemove(CollectionItem parent,  Set<Item> items);
+    default void beforeRemove(CollectionItem parent,  Set<Item> items) {
+    }
 
     /**
      * Intercepter executed after removing an item from a collection.
 
      * @param parent CollectionItem
      * @param items Set<Item> to remove
      */
-    public void afterRemove(CollectionItem parent, Set<Item> items);
-}
+    default void afterRemove(CollectionItem parent, Set<Item> items) {
+    }
+}

cosmo-api/src/main/java/org/unitedinternet/cosmo/service/interceptors/EventUpdateHandler.java

@@ -37,7 +37,8 @@ public interface EventUpdateHandler {
      * @param children
      *             children to update
      */
-    public void beforeUpdate(CollectionItem parent, Set<ContentItem> contentItems);
+    default void beforeUpdate(CollectionItem parent, Set<ContentItem> contentItems) {
+    }
 
     /**
      * This method contains the code inserted after an event to be updated.
@@ -57,5 +58,6 @@ public interface EventUpdateHandler {
      * @param children
      *             children to update
      */
-    public void afterUpdate(CollectionItem parent, Set<ContentItem> contentItems);
+    default void afterUpdate(CollectionItem parent, Set<ContentItem> contentItems) {
+    }
 }