docs: public static void put(String key, String val) throws IllegalArgumentException {
          if (key == null) {
              throw new IllegalArgumentException("key parameter cannot be null");
          }
          if (mdcAdapter == null) {
              throw new IllegalStateException("MDCAdapter cannot be null. See also " + NULL_MDCA_URL);
          }
          mdcAdapter.put(key, val);
      }