Declarative config: add service detector by default

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/resources/ResourceCustomizerProvider.java

@@ -11,7 +11,7 @@
 import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.ExperimentalResourceDetectionModel;
 import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.ExperimentalResourceDetectorModel;
 import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.ResourceModel;
-import java.util.Collections;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
@@ -26,8 +26,10 @@ public class ResourceCustomizerProvider implements DeclarativeConfigurationCusto
 
   // opentelemetry-javaagent-distribution: adds "distro.name" and "distro.version" attributes
   // (DistroComponentProvider in this package)
+  // service: adds "service.name" and "service.instance.id" attributes
+  // (https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/ServiceResourceDetector.java)
   private static final List<String> REQUIRED_DETECTORS =
-      Collections.singletonList("opentelemetry-javaagent-distribution");
+      Arrays.asList("opentelemetry-javaagent-distribution", "service");
 
   @Override
   public void customize(DeclarativeConfigurationCustomizer customizer) {

javaagent-tooling/src/test/java/io/opentelemetry/javaagent/tooling/resources/ResourceCustomizerProviderTest.java

@@ -27,7 +27,10 @@ void customize() {
               try {
                 assertThat(objectMapper.writeValueAsString(configurationModel.getResource()))
                     .isEqualTo(
-                        "{\"attributes\":[],\"detection/development\":{\"detectors\":[{\"opentelemetry-javaagent-distribution\":null}]}}");
+                        "{\"attributes\":[],\"detection/development\":{\"detectors\":["
+                            + "{\"service\":null},"
+                            + "{\"opentelemetry-javaagent-distribution\":null}"
+                            + "]}}");
               } catch (JsonProcessingException e) {
                 throw new AssertionError(e);
               }

smoke-tests/src/test/groovy/io/opentelemetry/smoketest/DeclarativeConfigurationSmokeTest.groovy

@@ -65,6 +65,9 @@ class DeclarativeConfigurationSmokeTest extends SmokeTest {
     then: "distro detector is added by customizer"
     hasResourceAttribute(traces, "telemetry.distro.name", "opentelemetry-javaagent")
 
+    then: "service detector is added by customizer"
+    findResourceAttribute(traces, "service.instance.id").findAny().isPresent()
+
     cleanup:
     stopTarget()