ParameterizedType parameterizedType = Types.newParameterizedType(Map.class, typesIn);
    typesIn[0] = null;
    typesIn[1] = null;

    Type[] typesOut = parameterizedType.getActualTypeArguments();
    typesOut[0] = null;
    typesOut[1] = null;

    assertEquals(String.class, parameterizedType.getActualTypeArguments()[0]);
    assertEquals(Integer.class, parameterizedType.getActualTypeArguments()[1]);
  }