Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract!
at java.util.ComparableTimSort.mergeHi(ComparableTimSort.java:835)
at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:453)
at java.util.ComparableTimSort.mergeForceCollapse(ComparableTimSort.java:392)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:191)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
at java.util.Arrays.sort(Arrays.java:472)
at java.util.Collections.sort(Collections.java:155)
at org.nuxeo.ecm.platform.web.common.session.NuxeoHttpSessionMonitor.getSortedSessions(NuxeoHttpSessionMonitor.java:149)
at org.nuxeo.ecm.admin.UsersActivityManager.getUserSessionsCount(UsersActivityManager.java:181)