Refresh session before switch to and from the channel manager ( from the content editor )

Problem: Session synchronization

The channel manager and the cms both have their own workflow instance and associated jcr session. It can happen that the sessions are out of sync and an exception is thrown ( javax.jcr.InvalidItemStateException: property /content/documents/hap/xmas-tree/xmas-tree[3]/hippostd:transferable: the property cannot be saved because it has been modified externally. ).

Solution

Refresh the session before and after each workflow operation in the channel manager.