code: public boolean containsKey(String inputKey) {
          String key = Normalizer.normalize(inputKey, Normalizer.NORMALIZE_LOWER);
          List<String> list = this.values.get(key);
          boolean rc = (null == list) ? false : !list.isEmpty();
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "containsKey: key=" + inputKey + " rc=" + rc);
          }
          return rc;
      }
docs: Query whether the target key exists with any values in this handler.
  
  @param inputKey
  @return boolean