Method useForNull

corpus/java/training/guava/base/Joiner.java:450–452

Returns a map joiner with the same behavior as this one, except automatically substituting nullText for any provided null keys or values.

(String nullText)

     * {@code nullText} for any provided null keys or values.
     */
    public MapJoiner useForNull(String nullText) {
      return new MapJoiner(joiner.useForNull(nullText), keyValueSeparator);
    }
  }

  CharSequence toString(Object part) {