Java Kata: Optional, Stream and List operations

kata-origin.java

ArrayList<String> list = new ArrayList<>();
String configs = params.getConfigurationIds(); // TODO: CSV list payload
if (configs != null && !configs.trim().isEmpty()) { // TODO: compare with call to StringValidator.isEmptyString() at line 5
    // split the list and put all items into the list
    if (!StringValidator.isEmptyString(configs)) { // TODO: method body like: string == null || string.trim().isEmpty()
        String[] feld = configs.split(",");
        if (feld != null) {
            if (feld.length > 0) {
                for (String dummy : feld) {
                    String tmp = dummy.trim();
                    if (tmp.length() > 0) {
                        list.add(tmp);
                    }
                }
            } else { // no comma
                list.add(configs);
            }
        }
    }
}