Fix SonarQube issues in multicast code

src/core/Addressable.java

 package core;
 
 /**
- * Classes implementing this interface have an address and
- * a certain type, which can be used for identification
+ * Classes implementing this interface have an address which can be used for identification
  *
  * Created by Marius Meyer on 10.03.17.
  */
 @FunctionalInterface
 public interface Addressable {
-
-    /**
-     * Defines different types of addresses.
-     */
-    enum AddressType {
-        /**
-         * An address of a single node
-         */
-        HOST,
-        /**
-         * An address of a group of nodes
-         */
-        GROUP
-    }
-
     /**
      * Returns the address of the object
      *