code: public static StorageKey copy(StorageKey toCopy) {
      return new StorageKey(toCopy.strategy, Lists.newArrayList(toCopy.values));
    }
docs: A convenience method to make a copy of a {@link StorageKey}.
  
  This is not a deep copy.
  
  @param toCopy a {@code StorageKey} to copy
  @return a new StorageKey with the same {@link PartitionStrategy} and content