code: public void setConversionPattern(final String conversionPattern) {
  		this.conversionPattern = OptionConverter.convertSpecialChars(conversionPattern);
  		head = createPatternParser(this.conversionPattern).parse();
  	}
docs: Set the <b>ConversionPattern</b> option. This is the string which
  controls formatting and consists of a mix of literal content and
  conversion specifiers.
  
  @param conversionPattern
  conversion pattern.