Sitewriter user cannot create a new document when having the userrole xm.content.editor or mx.content.author

if (documentAdditionWorkflowCategory.equals(category)) {

                    // added new document : because the document must be in 'preview' availability, we now set this explicitly
                    if (addedNode.isNodeType("hippostd:publishable")) {
                        log.info("Added document '{}' is pusblishable so set status to preview.",
                                addedNode.getPath());
                        addedNode.setProperty("hippostd:state", "unpublished");
                        addedNode.setProperty(HippoNodeType.HIPPO_AVAILABILITY, new String[] {"preview"});
                    } else {
                        log.info("Added document '{}' is not publishable so set status to live & preview directly.",
                                addedNode.getPath());
                        addedNode.setProperty(HippoNodeType.HIPPO_AVAILABILITY, new String[] {"live", "preview"});
                    }

                    if (addedNode.isNodeType("hippostd:publishableSummary")) {
                        addedNode.setProperty("hippostd:stateSummary", "new");
                    }
                    addedNode.getSession().save();
                }

if (documentAdditionWorkflowCategory.equals(category)) {

                    // commit the editable instance that was created

                    Workflow docWf = getWorkflow(documentNodeWorkflowCategory, getHandleForDocumentWorkflow(addedNode)););
                    if (docWf instanceof DocumentWorkflow) {
                        ((DocumentWorkflow)docWf).commitEditableInstance();
                    } else {
                        throw new ObjectBeanPersistenceException(String.format("Failed to commit editable instance of newly created " +
                                "node '%s'", addedNode.getPath()));
                    }

                }