update openJdk to 15

Author: Psilo

.travis.yml

@@ -27,7 +27,7 @@ branches:
     - master
 language: java
 jdk:
-    - openjdk14
+    - openjdk15
 before_install:
     - git clone https://github.com/UnterrainerInformatik/Travis-Scripts.git travis
     - source travis/functions.Java.sh

pom.xml

@@ -17,7 +17,7 @@
 
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>mqtt-client</artifactId>
-	<version>0.0.3</version>
+	<version>0.0.4</version>
 	<name>MqttClient</name>
 	<packaging>jar</packaging>