rule "firstNonNull"
when true
then
    set_field(field: "not_found", value: first_non_null([$message.null, $message.null]));
    set_field(field: "first_found", value: first_non_null(["first", $message.no, "c", $message.null]));
    set_field(field: "middle_found", value: first_non_null([$message.null, "middle", "e"]));
    set_field(field: "last_found", value: first_non_null([$message.null, $message.null, $message.null, $message.null, "last"]));

    set_field(field: "list_found", value: first_non_null([$message.null, ["a", "b"], "last"]));
    set_field(field: "int_found", value: first_non_null([1 ,$message.null]));
end
