Adds the ability to configure things needed by stackdriver

We will eventually need to change the encoder to use their format. Also,
stackdriver does not support shared spans.

pom.xml

@@ -272,9 +272,9 @@
 		<spring-cloud-stream.version>Elmhurst.BUILD-SNAPSHOT</spring-cloud-stream.version>
 		<spring-cloud-netflix.version>2.0.0.BUILD-SNAPSHOT</spring-cloud-netflix.version>
 		<spring-cloud-openfeign.version>2.0.0.BUILD-SNAPSHOT</spring-cloud-openfeign.version>
-		<brave.version>4.18.0</brave.version>
+		<brave.version>4.18.1</brave.version>
 		<!-- Version set until zipkin-junit gets defined in Brave BOM -->
-		<zipkin.version>2.5.1</zipkin.version>
+		<zipkin.version>2.6.1</zipkin.version>
 		<spring-security-boot-autoconfigure.version>2.0.0.RELEASE</spring-security-boot-autoconfigure.version>
 	</properties>
 

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/autoconfig/SleuthProperties.java

@@ -34,6 +34,9 @@ public class SleuthProperties {
 	/** When true, generate 128-bit trace IDs instead of 64-bit ones. */
 	private boolean traceId128 = false;
 
+	/** True means the tracing system supports sharing a span ID between a client and server. */
+	private boolean supportsJoin = true;
+
 	/**
 	 * List of baggage key names that should be propagated out of process.
 	 * These keys will be prefixed with `baggage` before the actual key.
@@ -70,6 +73,14 @@ public class SleuthProperties {
 		this.traceId128 = traceId128;
 	}
 
+	public boolean isSupportsJoin() {
+		return this.supportsJoin;
+	}
+
+	public void setSupportsJoin(boolean supportsJoin) {
+		this.supportsJoin = supportsJoin;
+	}
+
 	public List<String> getBaggageKeys() {
 		return this.baggageKeys;
 	}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.java

@@ -74,6 +74,7 @@ public class TraceAutoConfiguration {
 				.currentTraceContext(currentTraceContext)
 				.spanReporter(adjustedReporter(reporter))
 				.traceId128Bit(sleuthProperties.isTraceId128())
+				.supportsJoin(sleuthProperties.isSupportsJoin())
 				.build();
 	}
 

spring-cloud-sleuth-zipkin/src/main/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.java

@@ -20,6 +20,7 @@ import java.util.concurrent.TimeUnit;
 
 import brave.sampler.Sampler;
 import zipkin2.Span;
+import zipkin2.codec.BytesEncoder;
 import zipkin2.reporter.AsyncReporter;
 import zipkin2.reporter.InMemoryReporterMetrics;
 import zipkin2.reporter.Reporter;
@@ -78,13 +79,20 @@ public class ZipkinAutoConfiguration {
 	public Reporter<Span> reporter(
 			ReporterMetrics reporterMetrics,
 			ZipkinProperties zipkin,
-			Sender sender
+			Sender sender,
+			BytesEncoder<Span> spanBytesEncoder
 	) {
 		return AsyncReporter.builder(sender)
 				.queuedMaxSpans(1000) // historical constraint. Note: AsyncReporter supports memory bounds
 				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
 				.metrics(reporterMetrics)
-				.build(zipkin.getEncoder());
+				.build(spanBytesEncoder);
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	public BytesEncoder<Span> spanBytesEncoder(ZipkinProperties zipkinProperties) {
+		return zipkinProperties.getEncoder();
 	}
 
 	@Bean