get subtasks with REST API

I'm trying to get the sub tasks of an issue with the REST API.

I've found this issue (#5338) that it should be possible.

But for my test query:

https://xxxx/issues/123.xml

I don't get any information about the sub taks of this issue.

Does anybody know how to get the sub tasks via the REST API?
Thank a lot.

Sorry, found the answer myself.
You have to add ?include=children,relations:

https://xxxx/issues/123.xml?include=children

(1-1/1)

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