code: public ClassLoader getExternalClassLoader()
      {
          Map<String,String> opts = _ap.getAnnotationProcessorEnvironment().getOptions();
          String classpath = opts.get("-classpath");
  
          if ( classpath != null )
          {
              String [] cpEntries = classpath.split( File.pathSeparator );
              ArrayList a = new ArrayList();
              for ( String e : cpEntries )
              {
                  try
                  {
                      File f = (new File(e)).getCanonicalFile();
                      URL u = f.toURL();
                      a.add(u);
                  }
                  catch (Exception ex)
                  {
                      System.err.println( "getExternalClassLoader(): bad cp entry=" + e );
                      System.err.println( "Exception processing e=" + ex );
                  }
              }
              URL [] urls = new URL[a.size()];
              urls = (URL[]) a.toArray(urls);
  
              return new URLClassLoader( urls, ControlChecker.class.getClassLoader() );
          }
  
          return null;
      }
docs: Returns a classloader that can be used to load external classes