code: public final void attribute(String name, boolean value) throws IllegalStateException, IllegalArgumentException, IOException {
          attribute(name, value ? "true" : "false");
      }
docs: Adds an attribute to the current element, with a <code>boolean</code> value. There must
  currently be an open element.
  <p />
  The attribute value is surrounded by the quotation mark character (see
  {@link #getQuotationMark()}).
  
  @param name  the name of the attribute, not <code>null</code>.
  @param value the value of the attribute.
  @throws IllegalStateException    if <code>getState() != {@link #START_TAG_OPEN}</code>.
  @throws IllegalArgumentException if <code>name == null</code>.
  @throws IOException              if an I/O error occurs; this will set the state to {@link #ERROR_STATE}.