private boolean valueEquals(V leftValue, V rightValue) {
        if (leftValue == rightValue) {
            return true;
        }
        if (leftValue == null || rightValue == null) {
            return false;
        }
        return leftValue.equals(rightValue);
    }
Value equals.

@param leftValue
        the left value
@param rightValue
        the right value
@return the boolean
core/common/src/main/java/com/alipay/sofa/rpc/common/struct/MapDifference.java