What about a "validationTarget" attribute ?

As I see it, this is a problem of not having where to put the annotation for the parameters tuple, there is no need for a special kind of constraint.

This is similar to:

class Bean {

    // I can validate a single non-null string
    @NotNull
    private String single;

    // how can I validate a list of non-null strings ?
    // without resorting to a specially-defined bean, using a wrapper bean for String
    // would be the same as using a wrapper-bean for the parameter tuple ...
    @Valid
    private List<String> list;

}

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