The ornamental design for a cap for packagingcontainer, as shown and described.
FIG. 1 is a front view of a cap for packaging container showing our new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a top side view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a sectional view thereof taken on line 5-5 of FIG. 1;
FIG. 6 is a perspective view thereof; and,
FIG. 7 is a reference view thereof showing a condition in use.
A rear view and a left side view are omitted because the rear view is identical to the front view and the left side view is identical to the right side view.
The broken line showing of FIG. 7 is environmental only and not part of the claimed design.