code: public final void register() throws IllegalStateException {
          validateNotNull(bundleContext, "bundleContext");
  
          synchronized (this) {
              if (pageServiceRegistration != null) {
                  throw new IllegalStateException(String.format("%s [%s] has been registered.", getClass()
                      .getSimpleName(), this));
              }
              if (pageClass != null) {
                  PaxWicketMountPoint mountPoint = pageClass.getAnnotation(PaxWicketMountPoint.class);
                  if (mountPoint != null) {
                      mountPointRegistration = new DefaultPageMounter(getApplicationName(), bundleContext);
                      mountPointRegistration.addMountPoint(mountPoint.mountPoint(), pageClass);
                      mountPointRegistration.register();
                  }
              }
              pageServiceRegistration = bundleContext.registerService(SERVICE_CLASSES, this, properties);
          }
      }
docs: <p>register.</p>
  
  @throws java.lang.IllegalStateException if any.