code: protected String calcCacheKey(String key) {
          switch (keyMode) {
          case HASH:
          case MONOPOLISTIC:
              return key;
          case NAMESPACE:
              return getName() + ":" + key;
          default:
              throw new IllegalStateException("Invalid key mode: " + keyMode);
          }
      }
docs: Calculates cache key based on the key mode.
  
  <ul>
  <li>HASH & MONOPOLISTIC mode: return the key as-is</li>
  <li>NAMESPACE mode: return {@code cache_name:key}</li>
  </ul>
  
  @param key
  @return