code: @Override
  	public Converter build() {
  		Converter builtConverter = this.converter;
  		if (builtConverter == null) {
  			builtConverter = new DefaultConverter();
  		}
  		if (builtConverter instanceof ConverterRegistry) {
  			for (SupportingConverter conv : delegates) {
  				((ConverterRegistry) builtConverter).register(conv);
  			}
  		}
  		return builtConverter;
  	}
docs: Build the converter:
  <ul>
  <li>If a custom converter is defined, use it</li>
  <li>If no custom converter, use {@link DefaultConverter}</li>
  <li>If {@link DefaultConverter} or custom converter that also implements
  {@link ConverterRegistry}, register all previously registered
  {@link SupportingConverter}s</li>
  </ul>