code: public boolean updateDefaultKeys(String from, String to) {
          if (null == from) {
              return false;
          }
          if (null == to) {
              return false;
          }
          if (StringUtils.equals(from, to)) {
              return false;
          }
          String value = this.defaultValues.remove(from);
          if (null == value) {
              return false;
          }
          this.defaultValues.put(to, value);
          return true;
      }
docs: Update a key
  @param from
  @param to
  @return true if there was a value to be moved.