fix: fix PolarisRouterServiceInstanceListSupplier npe with reactive feign (#927)

CHANGELOG.md

@@ -9,3 +9,4 @@
 - [feature: improve circuit breaker usage.](https://github.com/Tencent/spring-cloud-tencent/pull/917)
 - [fix:fix nacos and consul registration.](https://github.com/Tencent/spring-cloud-tencent/pull/922)
 - [Documentation content changes: add circuitbreaker readme.](https://github.com/Tencent/spring-cloud-tencent/pull/931)
+- [fix: fix PolarisRouterServiceInstanceListSupplier npe with reactive feign.](https://github.com/Tencent/spring-cloud-tencent/pull/927)

spring-cloud-starter-tencent-polaris-router/src/main/java/com/tencent/cloud/polaris/router/PolarisRouterServiceInstanceListSupplier.java

@@ -97,6 +97,7 @@ public class PolarisRouterServiceInstanceListSupplier extends DelegatingServiceI
 		PolarisRouterContext routerContext = null;
 
 		DefaultRequestContext requestContext = (DefaultRequestContext) request.getContext();
+		if (requestContext != null) {
 			if (requestContext instanceof RequestDataContext) {
 				routerContext = buildRouterContext(((RequestDataContext) requestContext).getClientRequest().getHeaders());
 			}
@@ -104,6 +105,7 @@ public class PolarisRouterServiceInstanceListSupplier extends DelegatingServiceI
 				routerContext = buildRouterContext(((PolarisLoadBalancerRequest<?>) requestContext.getClientRequest()).getRequest()
 						.getHeaders());
 			}
+		}
 
 		if (routerContext == null) {
 			// return all servers if router context is null.

spring-cloud-starter-tencent-polaris-router/src/test/java/com/tencent/cloud/polaris/router/PolarisRouterServiceInstanceListSupplierTest.java

@@ -38,7 +38,9 @@ import com.tencent.cloud.polaris.router.config.properties.PolarisRuleBasedRouter
 import com.tencent.cloud.polaris.router.interceptor.MetadataRouterRequestInterceptor;
 import com.tencent.cloud.polaris.router.interceptor.NearbyRouterRequestInterceptor;
 import com.tencent.cloud.polaris.router.interceptor.RuleBasedRouterRequestInterceptor;
+import com.tencent.cloud.polaris.router.resttemplate.PolarisLoadBalancerRequest;
 import com.tencent.cloud.polaris.router.spi.RouterRequestInterceptor;
+import com.tencent.cloud.polaris.router.spi.RouterResponseInterceptor;
 import com.tencent.polaris.api.exception.PolarisException;
 import com.tencent.polaris.api.pojo.DefaultInstance;
 import com.tencent.polaris.api.pojo.DefaultServiceInstances;
@@ -63,6 +65,7 @@ import reactor.core.publisher.Flux;
 
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.DefaultRequest;
+import org.springframework.cloud.client.loadbalancer.DefaultRequestContext;
 import org.springframework.cloud.client.loadbalancer.RequestData;
 import org.springframework.cloud.client.loadbalancer.RequestDataContext;
 import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
@@ -219,7 +222,7 @@ public class PolarisRouterServiceInstanceListSupplierTest {
 			setTransitiveMetadata();
 
 			PolarisRouterServiceInstanceListSupplier polarisSupplier = new PolarisRouterServiceInstanceListSupplier(
-					delegate, routerAPI, requestInterceptors, null);
+					delegate, routerAPI, requestInterceptors, Collections.singletonList(new TestRouterResponseInterceptor()));
 
 			ProcessRoutersResponse assembleResponse = assembleProcessRoutersResponse();
 			when(routerAPI.processRouters(any())).thenReturn(assembleResponse);
@@ -279,6 +282,30 @@ public class PolarisRouterServiceInstanceListSupplierTest {
 		}
 	}
 
+	@Test
+	public void testGet03() {
+		try (MockedStatic<ApplicationContextAwareUtils> mockedApplicationContextAwareUtils = Mockito.mockStatic(ApplicationContextAwareUtils.class)) {
+			mockedApplicationContextAwareUtils.when(() -> ApplicationContextAwareUtils.getProperties(anyString()))
+					.thenReturn(testCallerService);
+			MetadataContextHolder.set(new MetadataContext());
+			mockedApplicationContextAwareUtils.when(() -> delegate.get())
+					.thenReturn(assembleServers());
+			mockedApplicationContextAwareUtils.when(() -> routerAPI.processRouters(any()))
+					.thenReturn(new ProcessRoutersResponse(new DefaultServiceInstances(null, new ArrayList<>())));
+
+			PolarisRouterServiceInstanceListSupplier polarisSupplier = new PolarisRouterServiceInstanceListSupplier(
+					delegate, routerAPI, requestInterceptors, null);
+
+			MockServerHttpRequest httpRequest = MockServerHttpRequest.get("/" + testCalleeService + "/users")
+					.header("k1", "v1")
+					.header(RouterConstant.ROUTER_LABEL_HEADER, "{\"k1\":\"v1\"}")
+					.queryParam("userid", "zhangsan")
+					.build();
+			DefaultRequestContext requestDataContext = new DefaultRequestContext(new PolarisLoadBalancerRequest(httpRequest, null), "blue");
+			DefaultRequest request = new DefaultRequest(requestDataContext);
+			assertThat(polarisSupplier.get(request).blockFirst().size()).isEqualTo(0);
+		}
+	}
 	private void setTransitiveMetadata() {
 		if (initTransitiveMetadata.compareAndSet(false, true)) {
 			// mock transitive metadata
@@ -325,4 +352,11 @@ public class PolarisRouterServiceInstanceListSupplierTest {
 		}
 		return Flux.fromIterable(Collections.singletonList(servers));
 	}
+
+	public class TestRouterResponseInterceptor implements RouterResponseInterceptor {
+		@Override
+		public void apply(ProcessRoutersResponse response, PolarisRouterContext routerContext) {
+			// do nothing
+		}
+	}
 }