Camera2: add toString implementation of LensShadingMap

        return HashCodeHelpers.hashCode(mRows, mColumns, elemsHash);

    }

    /**

     * Return the LensShadingMap as a string representation.

     *

     * <p> {@code "LensShadingMap{R:([%f, %f, ... %f], ... [%f, %f, ... %f]), G_even:([%f, %f, ...

     *  %f], ... [%f, %f, ... %f]), G_odd:([%f, %f, ... %f], ... [%f, %f, ... %f]), B:([%f, %f, ...

     *  %f], ... [%f, %f, ... %f])}"},

     * where each {@code %f} represents one gain factor and each {@code [%f, %f, ... %f]} represents

     * a row of the lens shading map</p>

     *

     * @return string representation of {@link LensShadingMap}

     */

    @Override

    public String toString() {

        StringBuilder str = new StringBuilder();

        str.append("LensShadingMap{");

        final String channelPrefix[] = {"R:(", "G_even:(", "G_odd:(", "B:("};

        for (int ch = 0; ch < COUNT; ch++) {

            str.append(channelPrefix[ch]);

            for (int r = 0; r < mRows; r++) {

                str.append("[");

                for (int c = 0; c < mColumns; c++) {

                    float gain = getGainFactor(ch, c, r);

                    str.append(gain);

                    if (c < mColumns - 1) {

                        str.append(", ");

                    }

                }

                str.append("]");

                if (r < mRows - 1) {

                    str.append(", ");

                }

            }

            str.append(")");

            if (ch < COUNT - 1) {

                str.append(", ");

            }

        }

        str.append("}");

        return str.toString();

    }

    private final int mRows;

    private final int mColumns;