defaultSerializationFormat property has no effect after upgrade to 2.0.0

After an upgrade of an application from Camunda Spring Boot Starter 1.3.0 to 2.0.0 (each with Camunda 7.6.0) I noticed that the setting of the default serialization format via camunda.bpm.defaultSerializationFormat=application/json has no effect anymore. The serialization format is always application/x-java-serialized-object.

I noticed that there is a unit test that covers this setting which passes. But in the end it does not work. I tried to find out what the problem is, but I did not manage to.

I probably can offer some kind of repro if that helps. But maybe the cause is obvious for you; in that case - I guess - the repo is not needed.

[FrVaBe]

I created a repro for this bug in my camunda/camunda-external-task-demo/ repository. Although I created this repository to do some investigantions on external task usage it contains a unit test that checks the serialization format. Use the CSBS-Issue-185-repro tag to check out the version that just basically handles the issue.

The configuration to use the JSON serialization was done in the application.properties file. The code is camunda spring boot starter version 1.3.0 / 2.0.0 compatible.

The test DefaultSerializationFormatTest.checkDefaultSerializationFormatHandling will fail with the Camunda Spring Boot Starter 2.0.0 version on the classpath (current dependency configuration). If Camunda Spring Boot Starter 1.3.0 is used instead, the test will pass (change the dependencies in the pom.xml).

[jangalinski]

I guess, this can be closed then …