docs: public URI expand(Map<String, ? extends Object> parameters) {
  
  		if (TemplateVariables.NONE.equals(variables)) {
  			return URI.create(baseUri);
  		}
  
  		Assert.notNull(parameters, "Parameters must not be null!");
  
  		org.springframework.web.util.UriTemplate baseTemplate = new org.springframework.web.util.UriTemplate(baseUri);
  		UriComponentsBuilder builder = UriComponentsBuilder.fromUri(baseTemplate.expand(parameters));
  
  		for (TemplateVariable variable : getOptionalVariables()) {
  			appendToBuilder(builder, variable, parameters.get(variable.getName()));
  		}
  
  		return builder.build().toUri();
  	}