code: private void set(String key, String... values) {
              String value = get(values);
              
              if (value != null) {
                  put(getLabel(key), value);
              }
          }
docs: Add first non-null/non-empty value to map.
  
  @param key The key to be added (is translated to a label value).
  @param values The list of possible values.