WheelViewLib/src/main/java/com/lukedeighton/wheelview/WheelView.java
public void setEmptyItemDrawable(Drawable drawable) {
        mEmptyItemDrawable = drawable;
        EMPTY_CACHE_ITEM.mDrawable = drawable;

        if (mWheelBounds != null) {
            invalidate();
        }
    }
public void setEmptyItemDrawable(Drawable drawable) {
        mEmptyItemDrawable = drawable;
        EMPTY_CACHE_ITEM.mDrawable = drawable;

        if (mWheelBounds != null) {
            invalidate();
        }
    }
Sets the empty item drawable that is drawn when outside of the adapter range.

@see #isEmptyItemPosition(int)