The ornamental design for a hollowsportsball, as shown and described.
FIG. 1 is a top and front perspective view of the hollow sports ball showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof; and,
FIG. 4 is left side view thereof. The right side view, the front view and the back view are the same as the left side view.
The broken line shown in FIGS. 1 and 4 is included for the purpose of illustrating a feature of the hollow sports ball that forms no part of the claimed design.