how to concat array of objects inside an object property

[Maxlufs]

Concat'ing arrays of primitive types: (OK)

var s1 = Joi.array().includes(Joi.number());
var s2 = Joi.array().includes(Joi.string());

var schema = s1.concat(s2);
Joi.validate([1,"a"], schema); 
// works fine. allow array of mixed of number and string

Concat'ing arrays of objects: (OK)

var s1 = Joi.array().includes(Joi.object().keys({
    "x": Joi.any()
}));
var s2 = Joi.array().includes(Joi.object().keys({
    "y": Joi.any()
}));

var schema = s1.concat(s2);
Joi.validate([{
    "x":1, 
    "y":2
}], schema);
// works fine. allow array of objects that contain both "x" and "y" properties

Concat'ing objects of arrays of objects: (not OK)

var s1 = Joi.object().keys({
    "prop": Joi.array().includes(Joi.object().keys({
        "x": Joi.any()
    }))
});
var s2 = Joi.object().keys({
    "prop": Joi.array().includes(Joi.object().keys({
        "y": Joi.any()
    }))
});

var schema = s1.concat(s2);
Joi.validate([{
    "prop": []
}], schema); 
// works fine

Joi.validate([{
    "prop": [{
        "x": 1
    }]
}], schema); 
// Uh-oh, prop at position 0 fails because x is not allowed

I can work around it by concat'ing the inner object first then include it into a schema of arrays
Is there a way to deep concat like this using built-in Joi.concat?

Thanks

[Marsup]

This issue has already been fixed in master and is to be released in 6.0.0 which shouldn't be too far. Meanwhile you can test if master works for your case.