Fix empty of enum form property of model created by Activiti modeler

modules/activiti-json-converter/src/main/java/org/activiti/editor/language/json/converter/BaseBpmnJsonConverter.java

@@ -520,6 +520,7 @@ public abstract class BaseBpmnJsonConverter implements EditorJsonConstants, Sten
                                 for (JsonNode enumNode : enumValuesNode) {
                                     if (enumNode.get("value") != null && enumNode.get("value").isNull() == false) {
                                         FormValue formValue = new FormValue();
+                                        formValue.setId(enumNode.get("value").asText());
                                         formValue.setName(enumNode.get("value").asText());
                                         formValueList.add(formValue);
                                     }