code: public static <S> ServiceFinder<S> loadInstalled(Class<S> service) {
      ClassLoader cl = ClassLoader.getSystemClassLoader();
      ClassLoader prev = null;
      while (cl != null) {
        prev = cl;
        cl = cl.getParent();
      }
      return load(service, prev);
    }
docs: Creates a new service loader for the given service type, using the
  extension class loader.
  
  <p> This convenience method simply locates the extension class loader,
  call it <tt><i>extClassLoader</i></tt>, and then returns
  
  <blockquote><pre>
  ServiceFinder.load(<i>service</i>, <i>extClassLoader</i>)</pre></blockquote>
  
  <p> If the extension class loader cannot be found then the system class
  loader is used; if there is no system class loader then the bootstrap
  class loader is used.
  
  <p> This method is intended for use when only installed providers are
  desired.  The resulting service will only find and load providers that
  have been installed into the current Java virtual machine; providers on
  the application's class path will be ignored.
  
  @param  <S> the class of the service type
  
  @param  service
  The interface or abstract class representing the service
  
  @return A new service loader