code: private void rebuildKey() {
  
          final StringBuilder sb = new StringBuilder();
  
          sb.append(classField().getCanonicalName()).append('|');
          for (final Object keyObject : this.keyPartList) {
              sb.append(buildObjectKey(keyObject)).append('|');
          }
          this.key = sb.toString();
      }
docs: (Re)-Build the string key by reading the keys list content.