Merge branch '2.1.x'

pom.xml

@@ -244,6 +244,12 @@
 				<version>3.8.0</version>
 				<scope>test</scope>
 			</dependency>
+			<dependency>
+				<groupId>net.jcip</groupId>
+				<artifactId>jcip-annotations</artifactId>
+				<version>1.0</version>
+				<scope>test</scope>
+			</dependency>
 		</dependencies>
 	</dependencyManagement>
 

spring-cloud-sleuth-core/pom.xml

@@ -336,6 +336,11 @@
 			<version>20.0</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>net.jcip</groupId>
+			<artifactId>jcip-annotations</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<profiles>

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/messaging/MessageHeaderPropagation.java

@@ -83,7 +83,11 @@ enum MessageHeaderPropagation
 			accessor.removeHeader(keyToRemove);
 			if (accessor instanceof NativeMessageHeaderAccessor) {
 				NativeMessageHeaderAccessor nativeAccessor = (NativeMessageHeaderAccessor) accessor;
-				nativeAccessor.removeNativeHeader(keyToRemove);
+				if (accessor.isMutable()) {
+					// 1184 native headers can be an immutable map
+					ensureNativeHeadersAreMutable(nativeAccessor)
+							.removeNativeHeader(keyToRemove);
+				}
 			}
 			else {
 				Object nativeHeaders = accessor
@@ -95,6 +99,26 @@ enum MessageHeaderPropagation
 		}
 	}
 
+	/**
+	 * Since for some reason, the native headers sometimes are immutable even though the
+	 * accessor says that the headers are mutable, then we have to ensure their
+	 * mutability. We do so by first making a mutable copy of the native headers, then by
+	 * removing the native headers from the headers map and replacing them with a mutable
+	 * copy. Workaround for #1184
+	 * @param nativeAccessor accessor containing (or not) native headers
+	 * @return modified accessor
+	 */
+	private static NativeMessageHeaderAccessor ensureNativeHeadersAreMutable(
+			NativeMessageHeaderAccessor nativeAccessor) {
+		Map<String, List<String>> nativeHeaderMap = nativeAccessor.toNativeHeaderMap();
+		nativeHeaderMap = nativeHeaderMap instanceof LinkedMultiValueMap ? nativeHeaderMap
+				: new LinkedMultiValueMap<>(nativeHeaderMap);
+		nativeAccessor.removeHeader(NativeMessageHeaderAccessor.NATIVE_HEADERS);
+		nativeAccessor.setHeader(NativeMessageHeaderAccessor.NATIVE_HEADERS,
+				nativeHeaderMap);
+		return nativeAccessor;
+	}
+
 	@Override
 	public void put(MessageHeaderAccessor accessor, String key, String value) {
 		try {
@@ -116,7 +140,7 @@ enum MessageHeaderPropagation
 		accessor.setHeader(key, value);
 		if (accessor instanceof NativeMessageHeaderAccessor) {
 			NativeMessageHeaderAccessor nativeAccessor = (NativeMessageHeaderAccessor) accessor;
-			nativeAccessor.setNativeHeader(key, value);
+			ensureNativeHeadersAreMutable(nativeAccessor).setNativeHeader(key, value);
 		}
 		else {
 			Object nativeHeaders = accessor

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/scheduling/TracingOnScheduledTests.java

@@ -22,6 +22,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import brave.Span;
 import brave.Tracing;
 import brave.sampler.Sampler;
+import net.jcip.annotations.NotThreadSafe;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.Before;
@@ -47,6 +48,7 @@ import static org.awaitility.Awaitility.await;
 @RunWith(SpringRunner.class)
 @SpringBootTest(classes = { ScheduledTestConfiguration.class })
 @DirtiesContext
+@NotThreadSafe
 public class TracingOnScheduledTests {
 
 	@Autowired

src/checkstyle/checkstyle-suppressions.xml

@@ -3,6 +3,7 @@
 	"-//Puppy Crawl//DTD Suppressions 1.1//EN"
 	"https://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
 <suppressions>
+	<suppress files=".*/test/.*" checks="JavadocVariable"/>
 	<suppress files=".*FinishedSpanHandlerTests.*" checks="LineLengthCheck"/>
 	<suppress files=".*GrpcTracingIntegrationTests.*" checks="LineLengthCheck"/>
 	<suppress files=".*IgnoreAutoConfiguredSkipPatternsIntegrationTests.*" checks="LineLengthCheck"/>