Remove unused imports from CSM Observability example (#11307)

Author: DNVindhya

examples/example-gcp-csm-observability/build.gradle

@@ -36,7 +36,6 @@ dependencies {
  implementation "io.grpc:grpc-gcp-csm-observability:${grpcVersion}"
  implementation "io.opentelemetry:opentelemetry-sdk:${openTelemetryVersion}"
  implementation "io.opentelemetry:opentelemetry-sdk-metrics:${openTelemetryVersion}"
- implementation "io.opentelemetry:opentelemetry-exporter-logging:${openTelemetryVersion}"
  implementation "io.opentelemetry:opentelemetry-exporter-prometheus:${openTelemetryPrometheusVersion}"
  compileOnly "org.apache.tomcat:annotations-api:6.0.53"
  runtimeOnly "io.grpc:grpc-xds:${grpcVersion}"

examples/example-gcp-csm-observability/src/main/java/io/grpc/examples/csmobservability/CsmObservabilityClient.java

@@ -20,13 +20,11 @@
 import io.grpc.Grpc;
 import io.grpc.InsecureChannelCredentials;
 import io.grpc.ManagedChannel;
-import io.grpc.ManagedChannelBuilder;
 import io.grpc.StatusRuntimeException;
 import io.grpc.examples.helloworld.GreeterGrpc;
 import io.grpc.examples.helloworld.HelloReply;
 import io.grpc.examples.helloworld.HelloRequest;
 import io.grpc.gcp.csm.observability.CsmObservability;
-import io.opentelemetry.exporter.logging.LoggingMetricExporter;
 import io.opentelemetry.exporter.prometheus.PrometheusHttpServer;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
@@ -69,7 +67,9 @@ public void greet(String name) {
  */
  public static void main(String[] args) throws Exception {
  String user = "world";
+ // Use xDS to establish contact with the server "helloworld:50051".
  String target = "xds:///helloworld:50051";
+ // The port on which prometheus metrics will be exposed.
  int prometheusPort = 9464;
  AtomicBoolean sendRpcs = new AtomicBoolean(true);
  if (args.length > 0) {

examples/example-gcp-csm-observability/src/main/java/io/grpc/examples/csmobservability/CsmObservabilityServer.java

@@ -38,33 +38,37 @@
 public class CsmObservabilityServer {
  private static final Logger logger = Logger.getLogger(CsmObservabilityServer.class.getName());
 
- private Server gRPCServer;
+ private Server server;
  private void start(int port) throws IOException {
- gRPCServer = Grpc.newServerBuilderForPort(port, InsecureServerCredentials.create())
+ server = Grpc.newServerBuilderForPort(port, InsecureServerCredentials.create())
  .addService(new GreeterImpl())
  .build()
  .start();
  logger.info("Server started, listening on " + port);
  }
 
  private void stop() throws InterruptedException {
- if (gRPCServer != null) {
- gRPCServer.shutdown().awaitTermination(30, TimeUnit.SECONDS);
+ if (server != null) {
+ server.shutdown().awaitTermination(30, TimeUnit.SECONDS);
  }
  }
 
+ /**
+ * Await termination on the main thread since the grpc library uses daemon threads.
+ */
  private void blockUntilShutdown() throws InterruptedException {
- if (gRPCServer != null) {
- gRPCServer.awaitTermination();
+ if (server != null) {
+ server.awaitTermination();
  }
  }
 
  /**
  * Main launches the server from the command line.
  */
  public static void main(String[] args) throws IOException, InterruptedException {
- /* The port on which the server should run. */
+ // The port on which the server should run.
  int port = 50051;
+ // The port on which prometheus metrics will be exposed.
  int prometheusPort = 9464;
 
  if (args.length > 0) {