How to validate uniqueness of nested struct inside slice

Question

I am using go-playground/validator

Does anyone know how to validate Code field for its uniqueness

type Product struct {
    Code      string `validate:"required"`
}

type UpdateValidation struct {
    Product    Product 
    Quantity   uint
}

type UpdateValidationSlice struct {
    SaleOrderItems []UpdateValidation `validate:"unique=Product,dive"` // unique=Product doesn't work
}

I have tried using unique=Product but it didn't work