code: public UriTemplate with(TemplateVariable variable) {
  
  		Assert.notNull(variable, "Template variable must not be null!");
  
  		return with(new TemplateVariables(variable));
  	}
docs: Creates a new {@link UriTemplate} with the given {@link TemplateVariable} added.
  
  @param variable must not be {@literal null}.
  @return will never be {@literal null}.