SOAP API: method getDescendents(String token, String pageId) does not work any more with Confluence 5.7.1

Hi,
we are using the cofluence SOAP API for synchronizing content between different confluence instances. On production we use 5.4.1. We are now testing 5.7.1 and experience problems with 5.7.1: The method

getDescendents(String token, String pageId)

from the SOAP API (see https://developer.atlassian.com/confdev/confluence-rest-api/confluence-xml-rpc-and-soap-apis/remote-confluence-methods) used to return the page descendants. Now it returns an empty list.
I noticed that on the Java API there are now two similar methods (with a different typing) on the Page Object:

getDescendents() [Deprecated]
getDescendants()

see https://docs.atlassian.com/confluence/latest/com/atlassian/confluence/pages/Page.html

Could it be that this rename caused the problems in the SOAP API?

Best regards
Bernd