The ornamental design for an umbrellacap, as shown and described.
FIG. 1 shows a perspective view of a design for an umbrella cap.
FIG. 2 shows a first side view of FIG. 1.
FIG. 3 shows a second side view of FIG. 1.
FIG. 4 shows a top view of FIG. 1; and,
FIG. 5 shows a perspective view of FIG. 1 in use in an umbrella.
The broken-line features in the figures are for illustrative purposes only and form no part of the claimed design. The umbrella in FIG. 5 is unclaimed environmental subject matter.