Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.5.0:java (default-cli) on project nextrtc-signaling-serverrror

You can build nextrtc-signaling-server project (https://github.com/mslosarz/nextrtc-signaling-server) using below command.

mvn clean package

If there is a main class (for example MySampleApplication.java) in a project with package (for example com.sample.my) then you can run that using below command.

mvn exec:java -Dexec.mainClass="com.sample.my.MySampleApplication"

If you want to develop new application using "nextrtc-signaling-server" then add below maven dependency in your maven project. Please refer https://nextrtc.org/archives/85

<dependency>
   <groupId>org.nextrtc.signalingserver</groupId>
   <artifactId>nextrtc-signaling-server</artifactId>
   <version>0.0.3</version>
</dependency>