Remove use of default method in interface

The use of a default method implementation in ServerEvents.java failed
to build for Android 8.0.

Remove the default method implementations and instead add empty method
bodies in the two places where it is needed.

Author: robert-s-ubi

ocpp-common/src/main/java/eu/chargetime/ocpp/ServerEvents.java

@@ -29,7 +29,7 @@ of this software and associated documentation files (the "Software"), to deal
 import java.util.UUID;
 
 public interface ServerEvents {
-  default void authenticateSession(SessionInformation information, String username, byte[] password) throws AuthenticationException {}
+  void authenticateSession(SessionInformation information, String username, byte[] password);
 
   void newSession(UUID sessionIndex, SessionInformation information);
 

ocpp-v1_6-test/src/main/java/eu/chargetime/ocpp/test/DummyHandlers.java

@@ -162,6 +162,10 @@ public FirmwareStatusNotificationConfirmation handleFirmwareStatusNotificationRe
 
   public ServerEvents generateServerEventsHandler() {
     return new ServerEvents() {
+      @Override
+      public void authenticateSession(SessionInformation information, String username, byte[] password) {
+      }
+
       @Override
       public void newSession(UUID sessionIndex, SessionInformation information) {
         currentSessionIndex = sessionIndex;

ocpp-v2_0-test/src/main/java/eu/chargetime/ocpp/test/FakeCentralSystem.java

@@ -71,6 +71,10 @@ public void started() throws Exception {
           host,
           port,
           new ServerEvents() {
+            @Override
+            public void authenticateSession(SessionInformation information, String username, byte[] password) {
+            }
+
             @Override
             public void newSession(UUID sessionIndex, SessionInformation information) {
               currentSession = sessionIndex;