code: public <T extends RestTemplate> T configure(T restTemplate) {
  		configureRequestFactory(restTemplate);
  		if (!CollectionUtils.isEmpty(this.messageConverters)) {
  			restTemplate.setMessageConverters(new ArrayList<>(this.messageConverters));
  		}
  		if (this.uriTemplateHandler != null) {
  			restTemplate.setUriTemplateHandler(this.uriTemplateHandler);
  		}
  		if (this.errorHandler != null) {
  			restTemplate.setErrorHandler(this.errorHandler);
  		}
  		if (this.rootUri != null) {
  			RootUriTemplateHandler.addTo(restTemplate, this.rootUri);
  		}
  		if (this.basicAuthentication != null) {
  			restTemplate.getInterceptors().add(this.basicAuthentication);
  		}
  		restTemplate.getInterceptors().addAll(this.interceptors);
  		if (!CollectionUtils.isEmpty(this.restTemplateCustomizers)) {
  			for (RestTemplateCustomizer customizer : this.restTemplateCustomizers) {
  				customizer.customize(restTemplate);
  			}
  		}
  		return restTemplate;
  	}
docs: Configure the provided {@link RestTemplate} instance using this builder.
  @param <T> the type of rest template
  @param restTemplate the {@link RestTemplate} to configure
  @return the rest template instance
  @see RestTemplateBuilder#build()
  @see RestTemplateBuilder#build(Class)