private String getFormatedString(List<String> newValue) {
        final String formated = newValue.stream()
            .filter(v -> !v.isEmpty())
            .collect(joining(","));
        
        if (formated == null || formated.isEmpty()) {
            return null;
        } else {
            return formated;
        }
    }
Removes any empty substrings and makes sure the entire string is either
{@code null} or non-empty.

@return  the formatted string
plugin-parent/enum-generator/src/main/java/com/speedment/plugins/enums/internal/ui/AddRemoveStringItem.java