Repository constructor NPE should be more verbose

[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] id can not be null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NullPointerException: id can not be null
	at org.apache.maven.wagon.repository.Repository.<init>(Repository.java:81)
	at org.apache.maven.artifact.repository.DefaultArtifactRepository.<init>(DefaultArtifactRepository.java:70)
	at org.apache.maven.artifact.repository.DefaultArtifactRepositoryFactory.createDeploymentArtifactRepository(DefaultArtifactRepositoryFactory.java:44)
	at org.apache.maven.project.ProjectUtils.buildDeploymentArtifactRepository(ProjectUtils.java:80)
	at org.apache.maven.project.DefaultMavenProjectBuilder.processProjectLogic(DefaultMavenProjectBuilder.java:1029)
	at org.apache.maven.project.DefaultMavenProjectBuilder.buildInternal(DefaultMavenProjectBuilder.java:880)
	at org.apache.maven.project.DefaultMavenProjectBuilder.buildFromSourceFileInternal(DefaultMavenProjectBuilder.java:508)
	at org.apache.maven.project.DefaultMavenProjectBuilder.build(DefaultMavenProjectBuilder.java:200)
	at org.apache.maven.DefaultMaven.getProject(DefaultMaven.java:604)
	at org.apache.maven.DefaultMaven.collectProjects(DefaultMaven.java:487)
	at org.apache.maven.DefaultMaven.collectProjects(DefaultMaven.java:560)
	at org.apache.maven.DefaultMaven.collectProjects(DefaultMaven.java:560)
	at org.apache.maven.DefaultMaven.getProjects(DefaultMaven.java:391)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:272)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
	at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
	at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
	at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
	at org.codehaus.classworlds.Launcher.main(Launcher.java:375)

    public Repository( String id, String url )
    {
        if ( id == null )
        {
            throw new NullPointerException( "id can not be null for Repository with url=" + url );
        }
        
        setId( id );

        if ( url == null )
        {
            throw new NullPointerException( "url can not be null for Repository with id=" + id );
        }
        
        setUrl( url );
    }