DO NOT MERGE

communication/src/main/java/datadog/communication/ddagent/DDAgentFeaturesDiscovery.java

@@ -4,7 +4,7 @@
 import static datadog.communication.http.OkHttpUtils.msgpackRequestBodyOf;
 import static datadog.communication.http.OkHttpUtils.prepareRequest;
 import static datadog.communication.serialization.msgpack.MsgPackWriter.FIXARRAY;
-import static datadog.trace.api.ProtocolVersion.V0_4;
+import static datadog.trace.api.ProtocolVersion.V1_0;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.emptySet;
 import static java.util.Collections.singletonList;
@@ -118,7 +118,7 @@ public DDAgentFeaturesDiscovery(
     this.agentBaseUrl = agentUrl;
     this.metricsEnabled = metricsEnabled;
     this.ignoreAgentVersionForStats = ignoreAgentVersionForStats;
-    this.protocolVersion = protocolVersion != null ? protocolVersion : V0_4;
+    this.protocolVersion = protocolVersion != null ? protocolVersion : V1_0;
     this.discoveryTimer = monitoring.newTimer("trace.agent.discovery.time");
     this.discoveryState = new State();
   }

communication/src/test/groovy/datadog/communication/ddagent/DDAgentFeaturesDiscoveryTest.groovy

@@ -87,7 +87,7 @@ class DDAgentFeaturesDiscoveryTest extends DDSpecification {
     V1_0     | V1_ENDPOINT
   }
 
-  def "null protocol version falls back to v0.4 trace endpoints"() {
+  def "null protocol version falls back to v1.0 trace endpoints"() {
     setup:
     OkHttpClient client = Mock(OkHttpClient)
     DDAgentFeaturesDiscovery features =
@@ -98,9 +98,10 @@ class DDAgentFeaturesDiscoveryTest extends DDSpecification {
 
     then:
     1 * client.newCall({ Request request -> request.url().toString() == "http://localhost:8125/info" }) >> { Request request -> infoResponse(request, "{}") }
+    1 * client.newCall({ Request request -> request.url().toString() == "http://localhost:8125/v1.0/traces" }) >> { Request request -> success(request) }
     0 * client.newCall({ Request request -> request.url().toString() == "http://localhost:8125/v0.5/traces" }) >> { Request request -> success(request) }
-    1 * client.newCall({ Request request -> request.url().toString() == "http://localhost:8125/v0.4/traces" }) >> { Request request -> success(request) }
-    features.getTraceEndpoint() == V04_ENDPOINT
+    0 * client.newCall({ Request request -> request.url().toString() == "http://localhost:8125/v0.4/traces" }) >> { Request request -> success(request) }
+    features.getTraceEndpoint() == V1_ENDPOINT
     0 * _
   }
 

dd-trace-api/src/main/java/datadog/trace/api/ConfigDefaults.java

@@ -92,7 +92,7 @@ public final class ConfigDefaults {
       Arrays.asList("user.id", "session.id", "account.id");
   static final boolean DEFAULT_JMX_FETCH_ENABLED = true;
 
-  static final String DEFAULT_TRACE_AGENT_PROTOCOL_VERSION = ProtocolVersion.V0_4.asConfigValue();
+  static final String DEFAULT_TRACE_AGENT_PROTOCOL_VERSION = ProtocolVersion.V1_0.asConfigValue();
 
   static final boolean DEFAULT_CLIENT_IP_ENABLED = false;