Build fails if artifact exists

overwriteArtifact is set to false. So I expect kind of message (like for release): Artifact *.zip already exists. Not creating instead of exception
java.io.IOException: {"message":"Validation Failed","request_id":"950033d3-dd64-11e4-8b9b-7bf14e76e838","documentation_url":"https://developer.github.com/v3","errors":[{"resource":"ReleaseAsset","code":"already_exists","field":"name"}]}
    at org.kohsuke.github.Requester.handleApiError(Requester.java:367)
    at org.kohsuke.github.Requester._to(Requester.java:202)
    at org.kohsuke.github.Requester.to(Requester.java:154)
    at org.kohsuke.github.GHRelease.uploadAsset(GHRelease.java:182)
    at de.jutzig.github.release.plugin.UploadMojo.execute(UploadMojo.java:173)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:132)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:355)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:155)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:584)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:216)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:160)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: java.io.IOException: Server returned HTTP response code: 422 for URL: https://uploads.github.com/repos/:user/:repo/releases/1135731/assets?name=name.zip
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1839)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1440)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
    at org.kohsuke.github.Requester.parse(Requester.java:323)
    at org.kohsuke.github.Requester._to(Requester.java:200)
    ... 24 more
jutzig / github-release-plugin

Build fails if artifact exists #13
