code: @SuppressWarnings("unchecked")
      public static <OBJ> OBJ getObject(String key) {
          if (!exists()) {
              throwThreadCacheNotInitializedException(key);
          }
          return (OBJ) threadLocal.get().get(key);
      }
docs: Get the value of the object by the key.
  @param <OBJ> The type of cached object.
  @param key The key of the object. (NotNull)
  @return The value of the object. (NullAllowed)