Support blocking LB health-checks with RestClient. Fix javadoc.

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalanced.java

@@ -26,8 +26,8 @@
 import org.springframework.beans.factory.annotation.Qualifier;
 
 /**
- * Annotation to mark a RestTemplate or WebClient bean to be configured to use a
- * LoadBalancerClient.
+ * Annotation to mark a RestTemplate, RestClient.Builder or WebClient.Builder bean to be
+ * configured to use a LoadBalancerClient.
  * @author Spencer Gibb
  */
 @Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD })

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/core/ServiceInstanceListSupplierBuilder.java

@@ -38,6 +38,7 @@
 import org.springframework.http.HttpStatus;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -202,6 +203,21 @@ public ServiceInstanceListSupplierBuilder withBlockingHealthChecks() {
 		return this;
 	}
 
+	/**
+	 * Adds a {@link HealthCheckServiceInstanceListSupplier} that uses user-provided
+	 * {@link RestClient} instance to the {@link ServiceInstanceListSupplier} hierarchy.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withBlockingRestClientHealthChecks() {
+		DelegateCreator creator = (context, delegate) -> {
+			RestClient restClient = context.getBean(RestClient.class);
+			LoadBalancerClientFactory loadBalancerClientFactory = context.getBean(LoadBalancerClientFactory.class);
+			return blockingHealthCheckServiceInstanceListSupplier(restClient, delegate, loadBalancerClientFactory);
+		};
+		this.creators.add(creator);
+		return this;
+	}
+
 	/**
 	 * Adds a {@link HealthCheckServiceInstanceListSupplier} that uses user-provided
 	 * {@link RestTemplate} instance to the {@link ServiceInstanceListSupplier} hierarchy.
@@ -360,6 +376,22 @@ private ServiceInstanceListSupplier blockingHealthCheckServiceInstanceListSuppli
 				}));
 	}
 
+	private ServiceInstanceListSupplier blockingHealthCheckServiceInstanceListSupplier(RestClient restClient,
+			ServiceInstanceListSupplier delegate, LoadBalancerClientFactory loadBalancerClientFactory) {
+		return new HealthCheckServiceInstanceListSupplier(delegate, loadBalancerClientFactory,
+				(serviceInstance, healthCheckPath) -> Mono.defer(() -> {
+					URI uri = UriComponentsBuilder.fromUriString(getUri(serviceInstance, healthCheckPath)).build()
+							.toUri();
+					try {
+						return Mono.just(HttpStatus.OK
+								.equals(restClient.get().uri(uri).retrieve().toBodilessEntity().getStatusCode()));
+					}
+					catch (Exception ignored) {
+						return Mono.just(false);
+					}
+				}));
+	}
+
 	static String getUri(ServiceInstance serviceInstance, String healthCheckPath) {
 		if (StringUtils.hasText(healthCheckPath)) {
 			String path = healthCheckPath.startsWith("/") ? healthCheckPath : "/" + healthCheckPath;