CmisNotSupportedException when accessing /docushare/ds_mobile_connector/atom

The AtomPub CMIS URL for Xerox DocuShare is supposed to be:

http://server/docushare/ds_mobile_connector/atom

PROBLEM: When I open a browser at that URL, I get the following exception:

HTTP Status 405 - notSupportednullorg.apache.chemistry.opencmis.commons.exceptions.CmisNotSupportedException    at com.xerox.docushare.opencmis.fileshare.DocuShareServiceFactory.getService(DocuShareServiceFactory.java:158)    at org.apache.chemistry.opencmis.server.impl.atompub.CmisAtomPubServlet.dispatch(CmisAtomPubServlet.java:278)    at org.apache.chemistry.opencmis.server.impl.atompub.CmisAtomPubServlet.service(CmisAtomPubServlet.java:231)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)    at com.xerox.docushare.amber.util.UTF8Filter.doFilter(UTF8Filter.java:28)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)    at java.lang.Thread.run(Thread.java:662)

Browsing at this URL is supposed to open an XML file describing the services of this server.
A CmisNotSupportedException at this point is quite unexpected.
What am I doing wrong? Or is it a know Xerox DocuShare bug?