MNT-17022 Errors in 5.1.1 when displaying any document linked to jBPM workflow

The getWorkflowsForContent method has been modified to catch the exception and return
one less item in the list of workflows to be processed when the workflow is jBPM (or
any other unregistered workflow - including future ones). It also logs a debug.
For example:

Workflow Component for engine id 'jbpm' is not registered. Ignored workflow on
workspace://SpacesStore/a0afc2d8-01e4-4fa5-a3b0-08d91d1fda03

Having examined the the rest of WorkflowServiceImpl (and spoken to the original
author), I don't believe there are other points in the code that we need worry about
for the UI perspective, even though there are 22 other methods directly calling the
method that throws the exception.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/BRANCHES/DEV/5.2.N/root@135753 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/workflow/WorkflowServiceImpl.java

@@ -1290,6 +1290,8 @@ public class WorkflowServiceImpl implements WorkflowService
         List<String> workflowIds = workflowPackageComponent.getWorkflowIdsForContent(packageItem);
         List<WorkflowInstance> workflowInstances = new ArrayList<WorkflowInstance>(workflowIds.size());
         for (String workflowId : workflowIds)
+        {
+            try
             {
                 String engineId = BPMEngineRegistry.getEngineId(workflowId);
                 WorkflowComponent component = getWorkflowComponent(engineId);
@@ -1299,6 +1301,12 @@ public class WorkflowServiceImpl implements WorkflowService
                     workflowInstances.add(instance);
                 }
             }
+            catch (WorkflowException componentForEngineNotRegistered)
+            {
+                String message = componentForEngineNotRegistered.getMessage();
+                logger.debug(message + ". Ignored workflow on " + packageItem);
+            }
+        }
         return workflowInstances;
     }