CoordinatesConverter { @TypeConverter public Coordinates fromString(String value) { return new Gson().fromJson(value, Coordinates.class); }  @TypeConverter String fromCoordinates(Coordinates coordinates); @TypeConverter Coordinates fromString(String value);  }
@Test public void fromStringThenConvertToCoordinates() { String value = "{\"lat\":1.0,\"lon\":1.0}"; Coordinates coordinates = new CoordinatesConverter().fromString(value); assertTrue(coordinates.getLatitude().blockingGet() == 1 && coordinates.getLongitude().blockingGet() == 1); }