Apache Camel Rest - v3.2.0 - Multipart file upload issue

Question

I am looking forward to achieve the multipart file upload with camel 3.2.0 version and JDK11.

I was able to successfully do the same with the older version of camel 2.x using the below code,

.post("/importFile")
            .id("importFile")
            .bindingMode(RestBindingMode.off)
            .consumes("multipart/form-data")
            .produces(IConstants.APPLICATION_JSON)
            .outType(String.class)
            .to("direct:importFile")
from("direct:importFile")
    .unmarshal()
    .mimeMultipart()
    .split().attachments()
    // further processing...

After upgrading the camel version from 2.x to 3.2.0, we were getting an compile time issue in the above code for ".attachments()". As a result, we replaced the from route by,

SplitAttachmentsExpression split = new SplitAttachmentsExpression();
from("direct:importFile")
    .unmarshal()
    .mimeMultipart()
    .split(split)
    // further processing...

However, after this when i debug the code i am getting null attachments. SplitAttachmentsExpression->evaluate()->exchange.getIn(AttachmentMessage.class).hasAttachments() ==> evaluates to false.

Am i missing anything here as part of the upgrade? Has the import file functionality changed with latest version of Camel? A quick help is highly appreciated as this was working earlier and now we are completely blocked!