OO-2144: fix validation and check if area keys list are null OR empty

src/main/java/org/olat/course/nodes/ENCourseNode.java

@@ -247,7 +247,7 @@ public class ENCourseNode extends AbstractAccessableCourseNode {
 				for (int i = 0; i < areas.length; i++) {
 					String trimmed = areas[i] != null ?
 							FilterFactory.getHtmlTagsFilter().filter(areas[i]).trim() : areas[i];
-					if (!trimmed.equals("") && !cev.existsGroup(trimmed)) {
+					if (!trimmed.equals("") && !cev.existsArea(trimmed)) {
 						missingNames.add(trimmed);
 					}
 				}
@@ -404,7 +404,7 @@ public class ENCourseNode extends AbstractAccessableCourseNode {
 		@SuppressWarnings("unchecked")
 		List<Long> areaKeys = (List<Long>) mc.get(ENCourseNode.CONFIG_AREA_IDS);
 		if(areaKeys == null) {
-			areaKeys = envMapper.toGroupKeyFromOriginalNames(areaNames);
+			areaKeys = envMapper.toAreaKeyFromOriginalNames(areaNames);
 		} else {
 			areaKeys = envMapper.toAreaKeyFromOriginalKeys(groupKeys);
 		}

src/main/java/org/olat/course/nodes/en/ENEditGroupAreaFormController.java

@@ -186,7 +186,7 @@ class ENEditGroupAreaFormController extends FormBasicController implements Gener
 	protected void initForm(FormItemContainer formLayout, Controller listener, UserRequest ureq) {
 		// groups
 		List<Long> groupKeys = moduleConfig.getList(ENCourseNode.CONFIG_GROUP_IDS, Long.class);
-		if(groupKeys == null) {
+		if(groupKeys == null || groupKeys.isEmpty()) {
 			String groupNames = (String) moduleConfig.get(ENCourseNode.CONFIG_GROUPNAME);
 			if(StringHelper.containsNonWhitespace(groupNames)) {
 				groupKeys = businessGroupService.toGroupKeys(groupNames, cev.getCourseGroupManager().getCourseEntry());
@@ -214,7 +214,7 @@ class ENEditGroupAreaFormController extends FormBasicController implements Gener
 
 		@SuppressWarnings("unchecked")
 		List<Long> areaKeys = (List<Long>)moduleConfig.get(ENCourseNode.CONFIG_AREA_IDS);
-		if(areaKeys == null) {
+		if(areaKeys == null || areaKeys.isEmpty()) {
 			String areaNames = (String) moduleConfig.get(ENCourseNode.CONFIG_AREANAME);
 			areaKeys = areaManager.toAreaKeys(areaNames, cev.getCourseGroupManager().getCourseResource());
 		}

src/main/java/org/olat/course/nodes/en/ENRunController.java

@@ -133,13 +133,13 @@ public class ENRunController extends BasicController implements GenericEventList
 
 		// Get groupnames from configuration
 		enrollableGroupKeys = moduleConfig.getList(ENCourseNode.CONFIG_GROUP_IDS, Long.class);
-		if(enrollableGroupKeys == null) {
+		if(enrollableGroupKeys == null || enrollableGroupKeys.isEmpty()) {
 			String groupNamesConfig = (String)moduleConfig.get(ENCourseNode.CONFIG_GROUPNAME);
 			enrollableGroupKeys = businessGroupService.toGroupKeys(groupNamesConfig, courseGroupManager.getCourseEntry());
 		}
 
 		enrollableAreaKeys = moduleConfig.getList(ENCourseNode.CONFIG_AREA_IDS, Long.class);
-		if(enrollableAreaKeys == null) {
+		if(enrollableAreaKeys == null || enrollableAreaKeys.isEmpty()) {
 			String areaInitVal = (String) moduleConfig.get(ENCourseNode.CONFIG_AREANAME);
 			enrollableAreaKeys = areaManager.toAreaKeys(areaInitVal, courseGroupManager.getCourseResource());
 		}