code: public static <TKey, TValue> MultivaluedMap<TKey, TValue>
              createMultivaluedMap(Map<TKey, TValue[]> data)
      {
          MultivaluedMap<TKey, TValue> target
              = new MultivaluedHashMap<TKey, TValue>();
  
          return putAll(target, data);
      }
docs: Create a {@code Map<TKey, TValue>} instance from a
  {@code Map<TKey, TValue[]} instance.
  
  @param data
  Input data.
  
  @return
  A new instance which contains all the entries
  in the input data. If the input data is {@code null}
  or empty, an empty {@code MultivaluedMap} instance
  is returned.