LOcale language converter null

LocaleConverter.java

/**
 
 Use this in persistent model
 
    @Column
    @NotNull
    @Convert(converter = LocaleConverter.class)
    private Locale language;

*/


import javax.persistence.AttributeConverter;
import java.util.Locale;

public class LocaleConverter implements AttributeConverter<Locale, String> {

    @Override
    public String convertToDatabaseColumn(Locale language) {
        return language == null ? null : language.toLanguageTag();
    }

    @Override
    public Locale convertToEntityAttribute(String language) {
        return language == null ? null : new Locale(language);
    }
}

LocaleConverterTest.java

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.runners.MockitoJUnitRunner;

import java.util.Locale;

import static org.assertj.core.api.Assertions.assertThat;

@RunWith(MockitoJUnitRunner.class)
public class LocaleConverterTest {

    private final static Locale LOCALE = new Locale("nl");
    private final static String VALUE = "nl";

    private LocaleConverter localeConverter;

    @Before
    public void setup() {
        localeConverter = new LocaleConverter();
    }

    @Test
    public void convertToDatabaseColumnConvertsCorrectly() {
        String result = localeConverter.convertToDatabaseColumn(LOCALE);
        assertThat(result).isEqualTo(VALUE);
    }

    @Test
    public void convertToDatabaseColumnConvertsNullToNull() {
        String result = localeConverter.convertToDatabaseColumn(null);
        assertThat(result).isNull();
    }

    @Test
    public void convertToEntityAttributeConvertsCorrectly() {
        Locale result = localeConverter.convertToEntityAttribute(VALUE);
        assertThat(result).isEqualTo(LOCALE);
    }

    @Test
    public void convertToEntityAttributeConvertsNullToNull() {
        Locale result = localeConverter.convertToEntityAttribute(null);
        assertThat(result).isNull();
    }
}