title: Exception attempting compile
body: <p>I am doing a build of a java application which uses jdk1.5 and maven 2.1.0. We re using Jenkins version 1.565.1. </p>
  
  <p>I keep getting the below error each time I do the build and the error doesnt make any sense. Has anyone come across the error before and has successfully resolved it?</p>
  
  <pre><code>    [INFO] [gwt:compile {execution: default}]
  [INFO] ------------------------------------------------------------------------
  [ERROR] BUILD ERROR
  [INFO] ------------------------------------------------------------------------
  [INFO] Exception attempting compile.
  
  [INFO] ------------------------------------------------------------------------
  [DEBUG] Trace
  org.apache.maven.lifecycle.LifecycleExecutionException: Exception attempting compile.
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:703)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:540)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:519)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:371)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:332)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:181)
      at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:356)
      at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:137)
      at org.apache.maven.cli.MavenCli.main(MavenCli.java:356)
      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:592)
      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)
  Caused by: org.apache.maven.plugin.MojoExecutionException: Exception attempting compile.
      at com.totsp.mavenplugin.gwt.CompileMojo.execute(CompileMojo.java:71)
      at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:483)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:678)
      ... 16 more
  Caused by: java.lang.NullPointerException
      at java.io.File.&lt;init&gt;(File.java:194)
      at com.totsp.mavenplugin.gwt.AbstractGWTMojo.buildClasspathList(AbstractGWTMojo.java:345)
      at com.totsp.mavenplugin.gwt.ScriptWriterUnix.writeCompileScript(ScriptWriterUnix.java:105)
      at com.totsp.mavenplugin.gwt.CompileMojo.execute(CompileMojo.java:63)
      ... 18 more
  </code></pre>