docs: @Override
      public JavaClass loadClass(/*@Nonnull*/ String className) throws ClassNotFoundException {
          if (className == null) {
              throw new IllegalArgumentException("className is null");
          }
          // if (className.indexOf('/') >= 0) throw new IllegalStateException();
          JavaClass javaClass = findClass(className);
          if (javaClass == null) {
              if (DEBUG) {
                  System.out.println("Looking up " + className + " on classpath");
                  dumpStack();
              }
              javaClass = urlClassPath.lookupClass(className);
              storeClass(javaClass);
          }
          return javaClass;
      }