@Test
public void returns_null_if_value_is_missing() throws Exception {

    IgnoreMissingValuesConverter converter = new IgnoreMissingValuesConverter("M", "m");
    Assert.assertEquals(null, converter.convert(""));
    Assert.assertEquals(null, converter.convert("M"));
    Assert.assertEquals(null, converter.convert("m"));
    Assert.assertEquals(1.0f, converter.convert("1.0"), 1e-3);
}