The ornamental design for a documentvalidator with a stacker, as shown and described.
FIG. 1 is a front elevation view of the document validator with the stacker according to the new design;
FIG. 2 is a rear elevation view with certain details shown in broken lines;
FIG. 3 is a right side elevation view;
FIG. 4 is a left side elevation view;
FIG. 5 is a plan view;
FIG. 6 is a bottom view with certain details shown in broken lines;
FIG. 7 is a front perspective view from the right upper side;
FIG. 8 is a front perspective view from the left upper side; and,
FIG. 9 is an enlarged fragmentary perspective view of a front bezel shown in FIG. 1. The broken line portions of FIGS. 2 and 6 form no part of the claimed design.