code: private URL findToolsJar() throws MojoExecutionException {
          final File javaHome = FileUtils.resolveFile(new File(File.pathSeparator), System.getProperty("java.home"));
          
          final List<File> toolsPaths = new ArrayList<File>();
          
          File file = null;
          if (SystemUtils.IS_OS_MAC_OSX) {
              file = FileUtils.resolveFile(javaHome, "../Classes/classes.jar");
              toolsPaths.add(file);
          }
          if (file == null || !file.exists()) {
              file = FileUtils.resolveFile(javaHome, "../lib/tools.jar");
              toolsPaths.add(file);
          }
          
          if (!file.exists()) {
              throw new MojoExecutionException("Could not find tools.jar at " + toolsPaths + " under java.home: " + javaHome);
          }
          getLog().debug("Using tools.jar: " + file);
          
          final URI fileUri = file.toURI();
          try {
              return fileUri.toURL();
          }
          catch (MalformedURLException e) {
              throw new MojoExecutionException("Could not generate URL from URI: " + fileUri, e);
          }
      }
docs: Figure out where the tools.jar file lives.