OO-4240: allow collecting task without task and optional

src/main/java/org/olat/course/nodes/gta/ui/GTACoachController.java

@@ -737,6 +737,11 @@ public class GTACoachController extends GTAAbstractController implements Assessm
 			submittedDocuments = documentsDir.listFiles(new SystemFilenameFilter(true, false));
 		}
 		
+		if(task == null && gtaNode.isOptional()) {
+			TaskProcess firstStep = gtaManager.firstStep(gtaNode);
+			task = gtaManager.createTask(null, taskList, firstStep, assessedGroup, assessedIdentity, gtaNode);
+		}
+		
 		int numOfDocs = submittedDocuments == null ? 0 : submittedDocuments.length;
 		task = gtaManager.collectTask(task, gtaNode, numOfDocs);
 		showInfo("run.documents.successfully.submitted");