private void setValue(String value) {
        if (value == null) {
            strings.clear();
        } else {
            strings.setAll(value.split(","));
        }
    }
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