minor: added logging statements to show if loosing openBIS sessions is due to...

minor: added logging statements to show if loosing openBIS sessions is due to the browser not sending a correct JSESSIONID cookie ?

SVN: 19821

openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/server/AbstractClientService.java

@@ -319,6 +319,11 @@ public abstract class AbstractClientService implements IClientService,
         }
         if (sessionToken == null)
         {
+            String sessionId = (httpSession != null) ? httpSession.getId() : null;
+            String logMessage =
+                    String.format("Unable to find session token in session [%s], sessionId=[%s]",
+                            httpSession, sessionId);
+            operationLog.info(logMessage);
             throw new InvalidSessionException("Session expired. Please login again.");
         }
         return sessionToken;