Fix sonar issues

Signed-off-by: SirWayne <dennis.melzer@bosch-si.com>

hawkbit-dmf-amqp/src/main/java/org/eclipse/hawkbit/amqp/AmqpControllerAuthentfication.java

@@ -36,7 +36,7 @@ import org.springframework.stereotype.Component;
 
 /**
  *
- *
+ * A controller which handles the amqp authentfication.
  */
 @Component
 public class AmqpControllerAuthentfication {

hawkbit-dmf-amqp/src/main/java/org/eclipse/hawkbit/amqp/AmqpMessageHandlerService.java

@@ -138,6 +138,13 @@ public class AmqpMessageHandlerService extends BaseAmqpService {
         return onMessage(message, type, tenant, getRabbitTemplate().getConnectionFactory().getVirtualHost());
     }
 
+    /**
+     * Executed on a authentication request.
+     * 
+     * @param message
+     *            the amqp message
+     * @return the rpc message back to supplier.
+     */
     @RabbitListener(queues = "${hawkbit.dmf.rabbitmq.authenticationReceiverQueue}", containerFactory = "listenerContainerFactory")
     public Message onAuthenticationRequest(final Message message) {
         checkContentTypeJson(message);
@@ -153,6 +160,19 @@ public class AmqpMessageHandlerService extends BaseAmqpService {
         }
     }
 
+    /**
+     * * Executed if a amqp message arrives.
+     * 
+     * @param message
+     *            the message
+     * @param type
+     *            the type
+     * @param tenant
+     *            the tenant
+     * @param virtualHost
+     *            the virtual host
+     * @return the rpc message back to supplier.
+     */
     public Message onMessage(final Message message, final String type, final String tenant, final String virtualHost) {
         checkContentTypeJson(message);
         final SecurityContext oldContext = SecurityContextHolder.getContext();

hawkbit-dmf-amqp/src/main/java/org/eclipse/hawkbit/amqp/BaseAmqpService.java

@@ -88,8 +88,7 @@ public class BaseAmqpService {
         return rabbitTemplate.getMessageConverter();
     }
 
-    protected final String getStringHeaderKey(final Message message, final String key,
-            final String errorMessageIfNull) {
+    protected String getStringHeaderKey(final Message message, final String key, final String errorMessageIfNull) {
         final Map<String, Object> header = message.getMessageProperties().getHeaders();
         final Object value = header.get(key);
         if (value == null) {
@@ -117,4 +116,5 @@ public class BaseAmqpService {
     protected void cleanMessageHeaderProperties(final Message message) {
         message.getMessageProperties().getHeaders().remove(AbstractJavaTypeMapper.DEFAULT_CLASSID_FIELD_NAME);
     }
+
 }