code: public void declaration(Writer out, char quotationMark) throws IllegalArgumentException, NullPointerException, IOException {
          if (quotationMark == '"') {
              out.write(_declarationDoubleQuotes);
          } else if (quotationMark == '\'') {
              out.write(_declarationSingleQuotes);
          }
      }
docs: Writes an XML declaration with double quotes.
  
  @param out           the character stream to write to, not <code>null</code>.
  @param quotationMark the quotationMark to use, either <code>'\''</code> or <code>'"'</code>.
  @throws IllegalArgumentException if
  <code>quotationMark != '\'' &amp;&amp; quotationMark != '"'</code>
  @throws NullPointerException     if <code>out == null</code>.
  @throws IOException              if an I/O error occurs.
  @since XMLenc 0.54