code: public static void remove(String key) 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.remove(key);
      }
docs: Remove the diagnostic context identified by the <code>key</code> parameter using
  the underlying system's MDC implementation. The <code>key</code> parameter
  cannot be null. This method does nothing if there is no previous value
  associated with <code>key</code>.
  
  @param key
  @throws IllegalArgumentException
  in case the "key" parameter is null