docs: public void open(String closer) {
          // always perform the check for valid API usage...
          if (closer == null) {
              throw new NullPointerException("closer == null");
          }
          // ...but avoid allocating an allocationSite if disabled
          if (this == NOOP || !ENABLED) {
              return;
          }
          String message = "Explicit termination method '" + closer + "' not called";
          allocationSite = new Throwable(message);
      }