The ornamental design for a beveragecontainer, as shown and described.
FIG. 1 is a perspective view of a beverage container showing my new design with the handle to the right and rear thereof, a straw protruding from the lid being shown in broken lines for illustrative purposes only and forming no part of the claimed design;
FIG. 2 is a side elevational view thereof with the handle to the left;
FIG. 3 is a side elevational view thereof with the handle to the front;
FIG. 4 is a side elevational view thereof with the handle to the rear;
FIG. 5 is a top plan view of the beverage container; and,