Google ADK tracing for Java

implementation 'com.google.adk:google-adk:0.4.0'
implementation 'io.opentelemetry:opentelemetry-api:1.49.0'
implementation 'io.opentelemetry:opentelemetry-sdk:1.49.0'
implementation 'io.opentelemetry:opentelemetry-exporter-otlp:1.49.0'
implementation 'com.arize:openinference-instrumentation-adk-java:0.1.2:all'
runtimeOnly 'org.slf4j:slf4j-simple:2.0.17'

import com.google.adk.agents.LlmAgent;
import com.google.adk.runner.InMemoryRunner;
import com.google.adk.sessions.Session;
import com.google.adk.tools.Annotations.Schema;
import com.google.adk.tools.FunctionTool;
import com.google.genai.types.Content;
import com.google.genai.types.Part;
import io.opentelemetry.api.common.AttributeKey;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator;
import io.opentelemetry.context.propagation.ContextPropagators;
import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporterBuilder;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.resources.Resource;
import io.opentelemetry.sdk.trace.SdkTracerProvider;
import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;
import java.time.Duration;
import java.util.Map;
import java.util.concurrent.TimeUnit;

private static SdkTracerProvider initializeOpenTelemetry() {
    Resource resource = Resource.getDefault().merge(Resource.create(Attributes.of(
        AttributeKey.stringKey("service.name"), "google-adk-java",
        AttributeKey.stringKey("openinference.project.name"),
            System.getenv().getOrDefault("PHOENIX_PROJECT_NAME", "google-adk-java")
    )));

    OtlpGrpcSpanExporterBuilder exporterBuilder = OtlpGrpcSpanExporter.builder()
        .setEndpoint(System.getenv().getOrDefault(
            "OTEL_EXPORTER_OTLP_ENDPOINT", "http://localhost:4317"))
        .setTimeout(Duration.ofSeconds(10));
    String phoenixApiKey = System.getenv("PHOENIX_API_KEY");
    if (phoenixApiKey != null && !phoenixApiKey.isEmpty()) {
        exporterBuilder.addHeader("Authorization", "Bearer " + phoenixApiKey);
    }

    SdkTracerProvider tracerProvider = SdkTracerProvider.builder()
        .addSpanProcessor(BatchSpanProcessor.builder(exporterBuilder.build())
            .setScheduleDelay(Duration.ofSeconds(1))
            .build())
        .setResource(resource)
        .build();
    OpenTelemetrySdk.builder()
        .setTracerProvider(tracerProvider)
        .setPropagators(ContextPropagators.create(W3CTraceContextPropagator.getInstance()))
        .buildAndRegisterGlobal();
    return tracerProvider;
}

public static Map<String, Object> getWeather(
    @Schema(name = "city", description = "The city to look up") String city) {
    return Map.of("city", city, "forecast", "sunny", "temperature_celsius", 21);
}

SdkTracerProvider tracerProvider = initializeOpenTelemetry();
try {
    LlmAgent agent = LlmAgent.builder()
        .name("weather_agent")
        .model("gemini-3.6-flash")
        .description("Answers weather questions with the getWeather tool.")
        .instruction("Always call getWeather before answering. Reply in one short sentence.")
        .tools(FunctionTool.create(Main.class, "getWeather"))
        .build();

    InMemoryRunner runner = new InMemoryRunner(agent);
    String userId = "visitor-123";
    Session session = runner.sessionService()
        .createSession(runner.appName(), userId).blockingGet();
    Content message = Content.fromParts(Part.fromText("What is the weather in Paris?"));
    runner.runAsync(userId, session.id(), message).blockingForEach(event -> {
        if (event.finalResponse()) {
            System.out.println("Agent: " + event.stringifyContent());
        }
    });
    tracerProvider.forceFlush().join(10, TimeUnit.SECONDS);
} finally {
    tracerProvider.shutdown().join(10, TimeUnit.SECONDS);
}