public List<String> getLabels() {
        JSONObject widgetConfiguration = getWidgetConfiguration();

        if (widgetConfiguration.has("filter") && widgetConfiguration.getBoolean("filter")) {
            show(); //listElt.isDisplayed only works when panel is visible

            return getItems().findElements(By.cssSelector("li.ui-selectonemenu-item")).stream()
                    .filter(listElt -> listElt.isDisplayed())
                    .map(e -> e.getDomProperty("innerHTML"))
                    .collect(Collectors.toList());
        }
        else {
            return getInput().findElements(By.tagName("option")).stream()
                    .map(e -> e.getDomProperty("innerHTML"))
                    .collect(Collectors.toList());
        }
    }
All labels independent of filter.
@return
primefaces-selenium/primefaces-selenium-components/src/main/java/org/primefaces/selenium/component/SelectOneMenu.java