public void setUnitColor(final Color COLOR) {
        if (null == unitColor) {
            _unitColor = COLOR;
            fireTileEvent(REDRAW_EVENT);
        } else {
            if (!unitColor.isBound()) {
                unitColor.set(COLOR);
            }
        }
    }
Defines the color that will be used to colorize the unit
of the tile.

@param COLOR
src/main/java/eu/hansolo/tilesfx/Tile.java