.valid()
.convertGroup( Default.class ).to( Foo.class )
.convertGroup( Bar.class ).to( Default.class )
.type( Runner.class )
.property( "paidEntryFee", FIELD )
.constraint( new AssertTrueDef().groups( Foo.class ) )
.constraint( new AssertTrueDef().message( "really, it must be true" ) );
config.addMapping( mapping );
Validator validator = config.buildValidatorFactory().getValidator();
Marathon marathon = new Marathon();
marathon.setName( "New York Marathon" );