Java Version set to 1.8

anonymous types replaced by lambda's
Method references used instead of Lambda's
Explicit type replaced by <>
travis.yml updated to java 1.8

perf/src/main/java/io/moquette/parser/netty/performance/ProtocolDecodingServer.java

@@ -152,12 +152,7 @@ public class ProtocolDecodingServer {
         System.out.println("Loop server started");
         startClientsTesting();
         //Bind  a shutdown hook
-        Runtime.getRuntime().addShutdownHook(new Thread() {
-            @Override
-            public void run() {
-                server.stop();
-            }
-        });
+        Runtime.getRuntime().addShutdownHook(new Thread(server::stop));
     }
 
     private static void startClientsTesting() throws MqttException, InterruptedException {

perf/src/main/java/io/moquette/parser/netty/performance/ProtocolPublishDecodingServer.java

@@ -104,12 +104,7 @@ public class ProtocolPublishDecodingServer {
         publishBombing();
         publishBombing();
         //Bind  a shutdown hook
-        Runtime.getRuntime().addShutdownHook(new Thread() {
-            @Override
-            public void run() {
-                server.stop();
-            }
-        });
+        Runtime.getRuntime().addShutdownHook(new Thread(server::stop));
     }
 
     private static void publishBombing() {