code: public final <S, T> void registerConverter(Class<S> input, Class<T> output, Converter<S, T> converter, Class<? extends Annotation> qualifier) {
  		registerConverter(new ConverterKey<S,T>(input, output, qualifier == null ? DefaultBinding.class : qualifier), converter);
  	}
docs: Register a Converter with the given input and output classes. Instances of the input class can be converted into
  instances of the output class
  @param input The input class
  @param output The output class
  @param converter The Converter to be registered
  @param qualifier The qualifier for which the converter must be registered