docs: public void setKey(String key) {
          Validate.notNull(key);
          key = key.trim();
          Validate.notEmpty(key); // trimming could potentially make empty, so validate here
          if (parent != null) {
              int i = parent.indexOfKey(this.key);
              if (i != Attributes.NotFound)
                  parent.keys[i] = key;
          }
          this.key = key;
      }