/// <summary>Compares two nodes including its children and qualifier.</summary>
        /// <param name="leftNode">an <c>XMPNode</c></param>
        /// <param name="rightNode">an <c>XMPNode</c></param>
        /// <returns>Returns true if the nodes are equal, false otherwise.</returns>
        /// <exception cref="XmpException">Forwards exceptions to the calling method.</exception>
        private static bool ItemValuesMatch(XmpNode leftNode, XmpNode rightNode)
        {
            var leftForm  = leftNode.Options;
            var rightForm = rightNode.Options;

            if (leftForm.Equals(rightForm))
            {
                return(false);
            }

            if (leftForm.GetOptions() == 0)
            {
                // Simple nodes, check the values and xml:lang qualifiers.
                if (!leftNode.Value.Equals(rightNode.Value))
                {
                    return(false);
                }
                if (leftNode.Options.HasLanguage != rightNode.Options.HasLanguage)
                {
                    return(false);
                }
                if (leftNode.Options.HasLanguage && !leftNode.GetQualifier(1).Value.Equals(rightNode.GetQualifier(1).Value))
                {
                    return(false);
                }
            }
            else
            {
                if (leftForm.IsStruct)
                {
                    // Struct nodes, see if all fields match, ignoring order.
                    if (leftNode.GetChildrenLength() != rightNode.GetChildrenLength())
                    {
                        return(false);
                    }

                    for (var it = leftNode.IterateChildren(); it.HasNext();)
                    {
                        var leftField  = (XmpNode)it.Next();
                        var rightField = XmpNodeUtils.FindChildNode(rightNode, leftField.Name, false);
                        if (rightField == null || !ItemValuesMatch(leftField, rightField))
                        {
                            return(false);
                        }
                    }
                }
                else
                {
                    // Array nodes, see if the "leftNode" values are present in the
                    // "rightNode", ignoring order, duplicates,
                    // and extra values in the rightNode-> The rightNode is the
                    // destination for AppendProperties.
                    Debug.Assert(leftForm.IsArray);
                    for (var il = leftNode.IterateChildren(); il.HasNext();)
                    {
                        var leftItem = (XmpNode)il.Next();
                        var match    = false;

                        for (var ir = rightNode.IterateChildren(); ir.HasNext();)
                        {
                            var rightItem = (XmpNode)ir.Next();
                            if (ItemValuesMatch(leftItem, rightItem))
                            {
                                match = true;
                                break;
                            }
                        }

                        if (!match)
                        {
                            return(false);
                        }
                    }
                }
            }
            return(true);
        }