this.disposition = descriptor.getDisposition();
this.md5 = descriptor.getContentMD5();
this.location = descriptor.getContentLocation();
final MimeDescriptor embeddedMessage = descriptor.embeddedMessage();
if (embeddedMessage == null) {
embeddedMessageStructure = null;
envelope = null;
} else {
embeddedMessageStructure = new MimeDescriptorStructure(allowExtensions, embeddedMessage, builder);