Makes dependencies of TokenRelayGatewayFilterFactory lazy.

Because of the use in the java dsl before oauth2 client auto configuration can run, the ReactiveOAuth2AuthorizedClientManager field of TokenRelayGatewayFilterFactory needs to be lazy.

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -845,16 +845,16 @@ public class GatewayAutoConfiguration {
 	@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
 	@ConditionalOnClass({ OAuth2AuthorizedClient.class, SecurityWebFilterChain.class, SecurityProperties.class })
 	@ConditionalOnEnabledFilter(TokenRelayGatewayFilterFactory.class)
-	@ConditionalOnBean(ReactiveClientRegistrationRepository.class)
 	protected static class TokenRelayConfiguration {
 
 		@Bean
 		public TokenRelayGatewayFilterFactory tokenRelayGatewayFilterFactory(
-				ReactiveOAuth2AuthorizedClientManager clientManager) {
+				ObjectProvider<ReactiveOAuth2AuthorizedClientManager> clientManager) {
 			return new TokenRelayGatewayFilterFactory(clientManager);
 		}
 
 		@Bean
+		@ConditionalOnBean(ReactiveClientRegistrationRepository.class)
 		public ReactiveOAuth2AuthorizedClientManager gatewayReactiveOAuth2AuthorizedClientManager(
 				ReactiveClientRegistrationRepository clientRegistrationRepository,
 				ServerOAuth2AuthorizedClientRepository authorizedClientRepository) {

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/TokenRelayGatewayFilterFactory.java

@@ -18,6 +18,7 @@ package org.springframework.cloud.gateway.filter.factory;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.security.oauth2.client.OAuth2AuthorizeRequest;
 import org.springframework.security.oauth2.client.OAuth2AuthorizedClient;
@@ -31,11 +32,11 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public class TokenRelayGatewayFilterFactory extends AbstractGatewayFilterFactory<Object> {
 
-	private final ReactiveOAuth2AuthorizedClientManager clientManager;
+	private final ObjectProvider<ReactiveOAuth2AuthorizedClientManager> clientManagerProvider;
 
-	public TokenRelayGatewayFilterFactory(ReactiveOAuth2AuthorizedClientManager clientManager) {
+	public TokenRelayGatewayFilterFactory(ObjectProvider<ReactiveOAuth2AuthorizedClientManager> clientManagerProvider) {
 		super(Object.class);
-		this.clientManager = clientManager;
+		this.clientManagerProvider = clientManagerProvider;
 	}
 
 	public GatewayFilter apply() {
@@ -59,6 +60,12 @@ public class TokenRelayGatewayFilterFactory extends AbstractGatewayFilterFactory
 		String clientRegistrationId = oauth2Authentication.getAuthorizedClientRegistrationId();
 		OAuth2AuthorizeRequest request = OAuth2AuthorizeRequest.withClientRegistrationId(clientRegistrationId)
 				.principal(oauth2Authentication).build();
+		ReactiveOAuth2AuthorizedClientManager clientManager = clientManagerProvider.getIfAvailable();
+		if (clientManager == null) {
+			return Mono.error(
+					new IllegalStateException("No ReactiveOAuth2AuthorizedClientManager bean was found. Did you include the "
+							+ "org.springframework.boot:spring-boot-starter-oauth2-client dependency?"));
+		}
 		// TODO: use Mono.defer() for request above?
 		return clientManager.authorize(request);
 	}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/TokenRelayGatewayFilterFactoryTests.java

@@ -24,6 +24,7 @@ import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Mono;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
 import org.springframework.http.HttpHeaders;
@@ -69,6 +70,7 @@ public class TokenRelayGatewayFilterFactoryTests {
 	}
 
 	@Before
+	@SuppressWarnings("unchecked")
 	public void init() {
 		request = MockServerHttpRequest.get("/hello").build();
 		mockExchange = MockServerWebExchange.from(request);
@@ -76,7 +78,9 @@ public class TokenRelayGatewayFilterFactoryTests {
 		when(filterChain.filter(any(ServerWebExchange.class))).thenReturn(Mono.empty());
 
 		authorizedClientManager = mock(ReactiveOAuth2AuthorizedClientManager.class);
-		filter = new TokenRelayGatewayFilterFactory(authorizedClientManager).apply();
+		ObjectProvider<ReactiveOAuth2AuthorizedClientManager> objectProvider = mock(ObjectProvider.class);
+		when(objectProvider.getIfAvailable()).thenReturn(authorizedClientManager);
+		filter = new TokenRelayGatewayFilterFactory(objectProvider).apply();
 	}
 
 	@After