code: public RestTemplateBuilder defaultMessageConverters() {
  		return new RestTemplateBuilder(this.detectRequestFactory, this.rootUri,
  				Collections.unmodifiableSet(
  						new LinkedHashSet<>(new RestTemplate().getMessageConverters())),
  				this.requestFactorySupplier, this.uriTemplateHandler, this.errorHandler,
  				this.basicAuthentication, this.restTemplateCustomizers,
  				this.requestFactoryCustomizer, this.interceptors);
  	}
docs: Set the {@link HttpMessageConverter HttpMessageConverters} that should be used with
  the {@link RestTemplate} to the default set. Calling this method will replace any
  previously defined converters.
  @return a new builder instance
  @see #messageConverters(HttpMessageConverter...)