In Poll Enrich EIP, get email attachments are empty

[Kangjian Zhang (contractor, iSoftStone)]

Hi All,

Let's say I need to wait for an event notification and then pull an attachments 
email like this:

Camel version 3.18.x

        from("servlet://foo?servletName=MyServlet")
                .loopDoWhile().simple("${exchangeProperty.CamelBatchComplete} 
== null || ${exchangeProperty.CamelBatchComplete} == false")
                        
.pollEnrich("imaps://{{mail.server}}?session=#oAuthSession&closeFolder=false&peek=true&folderName={{mail.sub.folder}}&sendEmptyMessageWhenIdle=true")
                        .process(exchange -> {
                            AttachmentMessage attachmentMessage = 
exchange.getIn(AttachmentMessage.class);
                            // Here attachments is null
                            Map<String, DataHandler> attachments = 
attachmentMessage.getAttachments();
                        })
                .end();

Same code, works fine in Camel 3.14.x but doesn't work in Camel 3.18.x.

After debugging, it was found that in Camel 3.16.x, the implementation of 
DefaultAttachmentMessage.java was upgraded.

The key point is the CamelAttachmentObjects property in the ExchangeProperty, 
which is placed in the Exchange property in version 3.14.x, and in the 
ExtendedExchange property in version 3.16.x, which results in the loss of the 
CamelAttachmentObjects property between different Exchange.

Details can be found in the link below line 274:
https://github.com/apache/camel/commit/0125a133a11cbdff57d459634bac276c10963387

I tried a solution as follows:

Camel version 3.18.x

        from("servlet://foo?servletName=MyServlet")
                .loopDoWhile().simple("${exchangeProperty.CamelBatchComplete} 
== null || ${exchangeProperty.CamelBatchComplete} == false")
                        
.pollEnrich("imaps://{{mail.server}}?session=#oAuthSession&closeFolder=false&peek=true&folderName={{mail.sub.folder}}&sendEmptyMessageWhenIdle=true",
                                ((oldExchange, newExchange) -> {
                                    // Deliver the attachment to the oldExchange
                                    
oldExchange.setIn(newExchange.getIn(AttachmentMessage.class));
                                    return oldExchange;
                                }))
                        .process(exchange -> {
                            AttachmentMessage attachmentMessage = 
exchange.getIn(AttachmentMessage.class);

                            Map<String, DataHandler> attachments = 
attachmentMessage.getAttachments();
                        })
                .end();

The above can solve the problem of not being able to get attachments, but there 
will be other properties missing.
Can you help with this? If information is missing, please do not hesitate to 
contact.

Thanks
Kangjian.