code: public RestTemplateBuilder errorHandler(ResponseErrorHandler errorHandler) {
  		Assert.notNull(errorHandler, "ErrorHandler must not be null");
  		return new RestTemplateBuilder(this.detectRequestFactory, this.rootUri,
  				this.messageConverters, this.requestFactorySupplier,
  				this.uriTemplateHandler, errorHandler, this.basicAuthentication,
  				this.restTemplateCustomizers, this.requestFactoryCustomizer,
  				this.interceptors);
  	}
docs: Set the {@link ResponseErrorHandler} that should be used with the
  {@link RestTemplate}.
  @param errorHandler the error handler to use
  @return a new builder instance