to declare your main class in the manifest file of your projet with maven. In pom add following (bold):

<build>
    <sourcedirectory>src</sourcedirectory>
    <plugins>
       <plugin>
          <groupid>org.apache.maven.plugins</groupid>
          <artifactid>maven-jar-plugin</artifactid>
          <configuration>
             <archive>
                <manifest>
                   <addclasspath>true</addclasspath>
                   <mainclass>net.witr.Application</mainclass>
                </manifest>
             </archive>
          </configuration>
       </plugin>
    </plugins>
</build>