fix: improve README

Author: patbeqo

contrib/temporal-opentelemetry-v2/README.md

@@ -3,6 +3,9 @@
 Module `io.temporal:temporal-opentelemetry-v2` provides replay-safe
 OpenTelemetry tracing, metrics, and logs for Temporal.
 
+> [!WARNING]
+> This module is experimental, and its API may change.
+
 ## Setup
 
 Use the same version as the rest of your Temporal Java SDK dependencies:
@@ -18,7 +21,13 @@ attach the plugin to your service stubs:
 
 ```java
 import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.exporter.otlp.logs.OtlpGrpcLogRecordExporter;
+import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporter;
 import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
+import io.opentelemetry.sdk.logs.SdkLoggerProvider;
+import io.opentelemetry.sdk.logs.export.BatchLogRecordProcessor;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
 import io.opentelemetry.sdk.trace.SdkTracerProvider;
 import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;
 import io.temporal.client.WorkflowClient;
@@ -34,6 +43,16 @@ ReplaySafeOpenTelemetry openTelemetry =
             SdkTracerProvider.builder()
                 .addSpanProcessor(
                     BatchSpanProcessor.builder(OtlpGrpcSpanExporter.builder().build()).build()))
+        .setMeterProviderBuilder(
+            SdkMeterProvider.builder()
+                .registerMetricReader(
+                    PeriodicMetricReader.builder(OtlpGrpcMetricExporter.builder().build())
+                        .build()))
+        .setLoggerProviderBuilder(
+            SdkLoggerProvider.builder()
+                .addLogRecordProcessor(
+                    BatchLogRecordProcessor.builder(OtlpGrpcLogRecordExporter.builder().build())
+                        .build()))
         .build();
 GlobalOpenTelemetry.set(openTelemetry);
 
@@ -51,6 +70,13 @@ Plugins configured on `WorkflowServiceStubsOptions` propagate to clients and
 workers created from those stubs. It can also be configured directly on
 `WorkflowClientOptions`.
 
+Build `ReplaySafeOpenTelemetry` before anything else uses the OpenTelemetry
+`Context`, and register it as the global before building the plugin. Otherwise,
+`OpenTelemetryPlugin.Builder.build()` throws `IllegalStateException`.
+
+Call `ReplaySafeOpenTelemetry.close()` after your workers and clients have
+stopped to export buffered telemetry and shut down its providers.
+
 ## Tracing
 
 The plugin propagates application trace context through Temporal headers.
@@ -81,7 +107,8 @@ try (Scope ignored = span.makeCurrent()) {
 
 ## Metrics
 
-Create synchronous metrics in workflow, client, and activity code with the standard OpenTelemetry API:
+Create metrics in workflow, client, and activity code with the standard
+OpenTelemetry API. Workflow code supports only synchronous instruments:
 
 ```java
 import io.opentelemetry.api.GlobalOpenTelemetry;

contrib/temporal-opentelemetry-v2/src/test/java/io/temporal/opentelemetry/v2/OtelTestBase.java

@@ -9,9 +9,9 @@
 import io.opentelemetry.sdk.logs.SdkLoggerProvider;
 import io.opentelemetry.sdk.logs.data.LogRecordData;
 import io.opentelemetry.sdk.logs.export.SimpleLogRecordProcessor;
-import io.opentelemetry.sdk.testing.exporter.InMemoryLogRecordExporter;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
 import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.testing.exporter.InMemoryLogRecordExporter;
 import io.opentelemetry.sdk.testing.exporter.InMemoryMetricReader;
 import io.opentelemetry.sdk.testing.exporter.InMemorySpanExporter;
 import io.opentelemetry.sdk.trace.SdkTracerProvider;