"MD5 returned by SQS does not match the calculation on the original request" when using AWS JSON protocol and message attributes with custom data types

[mgocd]

Description

When receiving a SQS message from ElasticMQ with an attribute with a custom data type (docs) using AWS JSON protocol (AWS Java SDK v1 >= 1.12.584 / v2 >= 2.21.19), the following exception is thrown:

com.amazonaws.AmazonClientException: MD5 returned by SQS does not match the calculation on the original request. (MD5 calculated by the message attributes: "b6ba7933bdd4077bb2cc8686b0146cfa", MD5 checksum returned: "6735a2d7fe7f0e962a51db579c2d92cb")
    at com.amazonaws.services.sqs.MessageMD5ChecksumHandler.receiveMessageResultMd5Check(MessageMD5ChecksumHandler.java:146)
    at com.amazonaws.services.sqs.MessageMD5ChecksumHandler.afterResponse(MessageMD5ChecksumHandler.java:87)
    at com.amazonaws.handlers.RequestHandler2Adaptor.afterResponse(RequestHandler2Adaptor.java:49)
    at com.amazonaws.http.AmazonHttpClient$RequestExecutor.afterResponse(AmazonHttpClient.java:1070)
...
        at com.amazonaws.services.sqs.AmazonSQSClient.receiveMessage(AmazonSQSClient.java:2339)

An example message with a custom data type when the error occurs:

var request = new SendMessageRequest(
                getQueueUrl(endpoint),
                "msg"
        );
request.setMessageAttributes(Map.of(
        "timestamp", new MessageAttributeValue()
                .withStringValue("1")
                .withDataType("Number.java.lang.Long")

Minimal reproducible example (Java): https://github.com/mgocd/elasticmq-custom-attribute-data-type-issue ElasticMQ version: 1.5.4

Analysis

This happens because MessageAttributeSupport ignores custom data types when serializing to JSON (so Number.java.lang.Long becomes Number), while SQSRestServerBuilder#md5AttributeDigest calculates MD5 digest correctly using the custom data type (Number.java.lang.Long).

Proposed solution

MessageAttributesSupport should use the custom data type when serializing to JSON.

A pull request has been proposed to fix the issue.

[micossow]

Released in v1.5.5