code: public static ClassInjector getInstance(ClassLoader loader) {
          ClassInjector injector = null;
  
          synchronized (cShared) {
              Reference ref = (Reference)cShared.get(loader);
              if (ref != null) {
                  injector = (ClassInjector)ref.get();
              }
              if (injector == null) {
                  injector = new ClassInjector(loader);
                  cShared.put(loader, new WeakReference(injector));
              }
              return injector;
          }
      }
docs: Returns a shared ClassInjector instance for the given ClassLoader.