public View getReorderedChildAt(int index) {
        if (index < 0 || index >= mReorderedIndices.length) {
            return null;
        }
        return getChildAt(mReorderedIndices[index]);
    }
Returns a View, which is reordered by taking {@link LayoutParams#order} parameters
into account.

@param index the index of the view
@return the reordered view, which {@link LayoutParams@order} is taken into account.
If the index is negative or out of bounds of the number of contained views,
returns {@code null}.
common/src/main/java/com/sxjs/common/widget/flexboxlayout/FlexboxLayout.java