@Override
    public ConfigDef config() {
        return CONFIG_DEF;
    }
@Test
    public void testConfig() {
        HasHeaderKey<SourceRecord> predicate = new HasHeaderKey<>();
        predicate.config().validate(Collections.singletonMap("name", "foo"));

        List<ConfigValue> configs = predicate.config().validate(Collections.singletonMap("name", ""));
        assertEquals(singletonList("Invalid value  for configuration name: String must be non-empty"), configs.get(0).errorMessages());
    }