@Override
    public String toString() {
        return StringUtil.simpleClassName(this) + "(default: " + defaultValue + ", map: " + map + ')';
    }
@Test
    public void testToString() {
        DomainNameMapping<String> mapping = new DomainNameMappingBuilder<String>("NotFound")
            .add("*.netty.io", "Netty")
            .add("downloads.netty.io", "Netty-Download")
            .build();

        assertEquals(
            "ImmutableDomainNameMapping(default: NotFound, map: {*.netty.io=Netty, downloads.netty.io=Netty-Download})",
            mapping.toString());
    }