Validate method
Implementation
@override
void Validate() {
super.Validate();
EwsUtilities.ValidateParamCollection(this.Attachments, "Attachments");
for (int i = 0; i < this.Attachments.length; i++) {
EwsUtilities.ValidateParam(this.Attachments[i]!.Id, "Attachment[$i].Id");
}
}