Return 0 status code on exception or invalid code

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/async/ExecutorBeanPostProcessor.java

@@ -272,9 +272,8 @@ private static <T> boolean anyFinalMethods(T object, Class<T> iface) {
 				method -> {
 					Method m = ReflectionUtils.findMethod(object.getClass(),
 							method.getName(), method.getParameterTypes());
-					return m != null &&
-							!ReflectionUtils.isObjectMethod(m) &&
-							Modifier.isFinal(m.getModifiers());
+					return m != null && !ReflectionUtils.isObjectMethod(m)
+							&& Modifier.isFinal(m.getModifiers());
 				});
 		return finalMethodPresent.get();
 	}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/TraceWebClientBeanPostProcessor.java

@@ -395,7 +395,18 @@ public String requestHeader(ClientRequest request, String name) {
 
 		@Override
 		public Integer statusCode(ClientResponse response) {
-			return response.statusCode().value();
+			int result = statusCodeAsInt(response);
+			return result != 0 ? result : null;
+		}
+
+		@Override
+		public int statusCodeAsInt(ClientResponse response) {
+			try {
+				return response.rawStatusCode();
+			}
+			catch (Exception dontCare) {
+				return 0;
+			}
 		}
 
 	}

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/TraceExchangeFilterFunctionHttpAdapterTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2013-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.web.client;
+
+import org.assertj.core.api.BDDAssertions;
+import org.junit.Test;
+import org.mockito.BDDMockito;
+
+import org.springframework.web.reactive.function.client.ClientResponse;
+
+public class TraceExchangeFilterFunctionHttpAdapterTests {
+
+	@Test
+	public void should_return_0_when_invalid_status_code_is_returned() {
+		ClientResponse clientResponse = BDDMockito.mock(ClientResponse.class);
+		BDDMockito.given(clientResponse.rawStatusCode())
+				.willThrow(new IllegalStateException("Boom"));
+		TraceExchangeFilterFunction.HttpAdapter adapter = new TraceExchangeFilterFunction.HttpAdapter();
+
+		Integer statusCode = adapter.statusCodeAsInt(clientResponse);
+
+		BDDAssertions.then(statusCode).isZero();
+	}
+
+	@Test
+	public void should_return_status_code_when_valid_status_code_is_returned() {
+		ClientResponse clientResponse = BDDMockito.mock(ClientResponse.class);
+		BDDMockito.given(clientResponse.rawStatusCode()).willReturn(200);
+		TraceExchangeFilterFunction.HttpAdapter adapter = new TraceExchangeFilterFunction.HttpAdapter();
+
+		Integer statusCode = adapter.statusCodeAsInt(clientResponse);
+
+		BDDAssertions.then(statusCode).isEqualTo(200);
+	}
+
+}