Fix NPE when empty body during retry (#2775)

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/ribbon/RetryableFeignLoadBalancer.java

@@ -137,7 +137,7 @@ public class RetryableFeignLoadBalancer extends FeignLoadBalancer implements Ser
 				}
 				Response response = request.client().execute(feignRequest, options);
 				if (retryPolicy.retryableStatusCode(response.status())) {
-					byte[] byteArray = StreamUtils.copyToByteArray(response.body().asInputStream());
+					byte[] byteArray = response.body() == null ? new byte[]{} : StreamUtils.copyToByteArray(response.body().asInputStream());
 					response.close();
 					throw new RibbonResponseStatusCodeException(RetryableFeignLoadBalancer.this.clientName, response,
 							byteArray, request.getUri());

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/ribbon/RetryableFeignLoadBalancerTests.java

@@ -79,6 +79,7 @@ import static org.junit.Assert.assertEquals;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyBoolean;
 import static org.mockito.Matchers.anyInt;
+import static org.mockito.Matchers.anyObject;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.doThrow;
@@ -228,6 +229,42 @@ public class RetryableFeignLoadBalancerTests {
 	}
 
 	@Test
+	public void executeRetryOnStatusCodeWithEmptyBody() throws Exception {
+		int retriesNextServer = 0;
+		when(this.config.get(MaxAutoRetriesNextServer,
+				DEFAULT_MAX_AUTO_RETRIES_NEXT_SERVER)).thenReturn(retriesNextServer);
+		doReturn(new Server("foo", 80)).when(lb).chooseServer(anyObject());
+		RibbonLoadBalancerContext lbContext = new RibbonLoadBalancerContext(lb, config);
+		SpringClientFactory clientFactory = mock(SpringClientFactory.class);
+		IClientConfig config = mock(IClientConfig.class);
+		doReturn(1).when(config).get(eq(CommonClientConfigKey.MaxAutoRetries), anyInt());
+		doReturn(retriesNextServer).when(config).get(eq(CommonClientConfigKey.MaxAutoRetriesNextServer), anyInt());
+		doReturn(true).when(config).get(eq(CommonClientConfigKey.OkToRetryOnAllOperations), eq(false));
+		doReturn(defaultConnectTimeout).when(config).get(eq(CommonClientConfigKey.ConnectTimeout));
+		doReturn(defaultReadTimeout).when(config).get(eq(CommonClientConfigKey.ReadTimeout));
+		doReturn("404").when(config).getPropertyAsString(eq(RibbonLoadBalancedRetryPolicy.RETRYABLE_STATUS_CODES),eq(""));
+		doReturn(config).when(clientFactory).getClientConfig(eq("default"));
+		doReturn(lbContext).when(clientFactory).getLoadBalancerContext(any(String.class));
+		RibbonLoadBalancedRetryPolicyFactory loadBalancedRetryPolicyFactory = new RibbonLoadBalancedRetryPolicyFactory(clientFactory);
+		HttpRequest springRequest = mock(HttpRequest.class);
+		Request feignRequest = Request.create("GET", "http://foo", new HashMap<String, Collection<String>>(),
+				new byte[]{}, StandardCharsets.UTF_8);
+		Client client = mock(Client.class);
+		FeignLoadBalancer.RibbonRequest request = new FeignLoadBalancer.RibbonRequest(client, feignRequest, new URI("http://foo"));
+		Response response = Response.builder().status(404).headers(new HashMap<String, Collection<String>>()).build();
+		Response fourOFourResponse = Response.builder().status(404).headers(new HashMap<String, Collection<String>>()).build();
+		doReturn(fourOFourResponse).doReturn(response).when(client).execute(any(Request.class), any(Request.Options.class));
+		MyBackOffPolicyFactory backOffPolicyFactory = new MyBackOffPolicyFactory();
+		RetryableFeignLoadBalancer feignLb = new RetryableFeignLoadBalancer(lb, config, inspector, loadBalancedRetryPolicyFactory,
+				backOffPolicyFactory);
+		FeignLoadBalancer.RibbonResponse ribbonResponse = feignLb.execute(request, null);
+		assertEquals(404, ribbonResponse.toResponse().status());
+		assertEquals(new Integer(0), ribbonResponse.toResponse().body().length());
+		verify(client, times(2)).execute(any(Request.class), any(Request.Options.class));
+		assertEquals(1, backOffPolicyFactory.getCount());
+	}
+
+	@Test
 	public void getRequestSpecificRetryHandler() throws Exception {
 		RibbonLoadBalancerContext lbContext = new RibbonLoadBalancerContext(lb, config);
 		SpringClientFactory clientFactory = mock(SpringClientFactory.class);