docs: public void removeAttribute(String name) {
          if (name == null) {
              throw new NullPointerException("don't set a NULL named attribute");
          }
          synchronized (mutex) {
              window.remove(name);
              if (deleteAttributes == null) {
                  deleteAttributes = new HashSet<String>(4);
                  deleteAttributes.add(name);
              }
          }
      }