title: java.lang.AssertionError thrown when using "maven-compiler-plugin"
body: <p>This is a follow up question of my <a href="https://stackoverflow.com/questions/34292102/jspc-maven-plugin-not-executed">earlier question</a>.  Now, I have the plugin running, but I don't see any result in <code>target/jsp-source</code>.  Here's what's in pom.xml</p>
  
  <pre><code>&lt;build&gt;
     &lt;plugins&gt;
        &lt;plugin&gt;
           &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
           &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
           &lt;version&gt;3.1&lt;/version&gt;
           &lt;configuration&gt;
              &lt;source&gt;1.8&lt;/source&gt;
              &lt;target&gt;1.8&lt;/target&gt;
           &lt;/configuration&gt;
        &lt;/plugin&gt;
  
        &lt;plugin&gt;
           &lt;groupId&gt;org.codehaus.mojo.jspc&lt;/groupId&gt;
           &lt;artifactId&gt;jspc-maven-plugin&lt;/artifactId&gt;
           &lt;version&gt;2.0-alpha-3&lt;/version&gt;
           &lt;executions&gt;
              &lt;execution&gt;
                 &lt;phase&gt;compile&lt;/phase&gt;
                 &lt;goals&gt;
                    &lt;goal&gt;compile&lt;/goal&gt;
                 &lt;/goals&gt;
              &lt;/execution&gt;
           &lt;/executions&gt;
           &lt;configuration&gt;
              &lt;inputwebxml&gt;${basedir}/src/main/webapp/WEB-INF/web.xml&lt;/inputwebxml&gt;
              &lt;sources&gt;
                 &lt;directory&gt;${basedir}/src/main/webapp/jsp&lt;/directory&gt;
                 &lt;includes&gt;
                    &lt;include&gt;**/*.jsp&lt;/include&gt;
                 &lt;/includes&gt;
              &lt;/sources&gt;
           &lt;/configuration&gt;
        &lt;/plugin&gt;
     &lt;/plugins&gt;
  &lt;/build&gt;
  </code></pre>
  
  <p>After I run <code>clean dependency:copy-dependencies install</code>, I have below exception thrown <code>Exception in thread "main" java.lang.AssertionError: Missing tools.jar at: /Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home/Classes/classes.jar. Expression: file.exists()</code></p>
  
  <pre><code>Exception in thread "main" java.lang.AssertionError: Missing tools.jar at: /Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home/Classes/classes.jar. Expression: file.exists()
     at org.codehaus.groovy.runtime.InvokerHelper.assertFailed(InvokerHelper.java:395)
     at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.assertFailed(ScriptBytecodeAdapter.java:683)
     at org.codehaus.mojo.jspc.CompilationMojoSupport.findToolsJar(CompilationMojoSupport.groovy:371)
     at org.codehaus.mojo.jspc.CompilationMojoSupport.this$4$findToolsJar(CompilationMojoSupport.groovy)
     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:497)
     at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
     at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:230)
     at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:912)
     at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrentN(ScriptBytecodeAdapter.java:78)
     at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrent0(ScriptBytecodeAdapter.java:112)
     at org.codehaus.mojo.jspc.CompilationMojoSupport.execute(CompilationMojoSupport.groovy:318)
     at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
     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:128)
     at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
     at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
     at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
     at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
     at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
     at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
     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:497)
     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)
  </code></pre>