Mark all public classes as final in the examples (#2846)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

examples/grpc/src/main/java/io/opentelemetry/example/grpc/HelloWorldClient.java

@@ -28,7 +28,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class HelloWorldClient {
+public final class HelloWorldClient {
   private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName());
   private final ManagedChannel channel;
   private final String serverHostname;
@@ -97,7 +97,7 @@ public class HelloWorldClient {
     }
   }
 
-  public class OpenTelemetryClientInterceptor implements ClientInterceptor {
+  public final class OpenTelemetryClientInterceptor implements ClientInterceptor {
 
     @Override
     public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(

examples/grpc/src/main/java/io/opentelemetry/example/grpc/HelloWorldClientStream.java

@@ -38,7 +38,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class HelloWorldClientStream {
+public final class HelloWorldClientStream {
   private static final Logger logger = Logger.getLogger(HelloWorldClientStream.class.getName());
   private final ManagedChannel channel;
   private final String serverHostname;
@@ -145,7 +145,7 @@ public class HelloWorldClientStream {
     }
   }
 
-  public class OpenTelemetryClientInterceptor implements ClientInterceptor {
+  public final class OpenTelemetryClientInterceptor implements ClientInterceptor {
 
     @Override
     public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(

examples/grpc/src/main/java/io/opentelemetry/example/grpc/HelloWorldServer.java

@@ -26,7 +26,7 @@ import java.net.InetSocketAddress;
 import java.util.logging.Logger;
 
 /** Server that manages startup/shutdown of a {@code Greeter} server. */
-public class HelloWorldServer {
+public final class HelloWorldServer {
   private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());
 
   private static final int PORT = 50051;

examples/http/src/main/java/io/opentelemetry/example/http/HttpClient.java

@@ -22,7 +22,7 @@ import java.net.URL;
 import java.net.URLConnection;
 import java.nio.charset.Charset;
 
-public class HttpClient {
+public final class HttpClient {
 
   // it's important to initialize the OpenTelemetry SDK as early in your applications lifecycle as
   // possible.

examples/http/src/main/java/io/opentelemetry/example/http/HttpServer.java

@@ -22,7 +22,7 @@ import java.io.OutputStream;
 import java.net.InetSocketAddress;
 import java.nio.charset.Charset;
 
-public class HttpServer {
+public final class HttpServer {
   // It's important to initialize your OpenTelemetry SDK as early in your application's lifecycle as
   // possible.
   private static final OpenTelemetry openTelemetry = ExampleConfiguration.initOpenTelemetry();

examples/jaeger/src/main/java/io/opentelemetry/example/jaeger/JaegerExample.java

@@ -4,7 +4,7 @@ import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.Tracer;
 
-public class JaegerExample {
+public final class JaegerExample {
 
   private final Tracer tracer;
 

examples/logging/src/main/java/io/opentelemetry/example/logging/ExampleConfiguration.java

@@ -14,7 +14,7 @@ import java.util.Collections;
  * All SDK management takes place here, away from the instrumentation code, which should only access
  * the OpenTelemetry APIs.
  */
-public class ExampleConfiguration {
+public final class ExampleConfiguration {
 
   /** The number of milliseconds between metric exports. */
   private static final long METRIC_EXPORT_INTERVAL_MS = 800L;

examples/logging/src/main/java/io/opentelemetry/example/logging/LoggingExporterExample.java

@@ -10,7 +10,7 @@ import io.opentelemetry.api.trace.Tracer;
  * An example of using {@link io.opentelemetry.exporter.logging.LoggingSpanExporter} and {@link
  * io.opentelemetry.exporter.logging.LoggingMetricExporter}.
  */
-public class LoggingExporterExample {
+public final class LoggingExporterExample {
   private static final String INSTRUMENTATION_NAME = LoggingExporterExample.class.getName();
 
   private final Tracer tracer;

examples/metrics/src/main/java/io/opentelemetry/example/metrics/DoubleCounterExample.java

@@ -20,7 +20,7 @@ import javax.swing.filechooser.FileSystemView;
  * Example of using {@link DoubleCounter} to count disk space used by files with specific
  * extensions.
  */
-public class DoubleCounterExample {
+public final class DoubleCounterExample {
   private static final OpenTelemetry openTelemetry = GlobalOpenTelemetry.get();
   private static final Tracer tracer =
       openTelemetry.getTracer("io.opentelemetry.example.metrics", "0.13.1");

examples/metrics/src/main/java/io/opentelemetry/example/metrics/LongCounterExample.java

@@ -18,7 +18,7 @@ import javax.swing.filechooser.FileSystemView;
 /**
  * Example of using {@link LongCounter} and {@link BoundLongCounter} to count searched directories.
  */
-public class LongCounterExample {
+public final class LongCounterExample {
   private static final OpenTelemetry openTelemetry = GlobalOpenTelemetry.get();
   private static final Tracer tracer =
       openTelemetry.getTracer("io.opentelemetry.example.metrics", "0.13.1");

examples/metrics/src/main/java/io/opentelemetry/example/metrics/LongValueObserverExample.java

@@ -10,7 +10,7 @@ import io.opentelemetry.api.metrics.common.Labels;
  * {@link LongValueObserver} updater sets a callback that gets executed every collection interval.
  * Useful for expensive measurements that would be wastefully to calculate each request.
  */
-public class LongValueObserverExample {
+public final class LongValueObserverExample {
 
   public static void main(String[] args) {
     Meter sampleMeter =

examples/otlp/src/main/java/io/opentelemetry/example/otlp/ExampleConfiguration.java

@@ -22,7 +22,7 @@ import java.util.concurrent.TimeUnit;
  * All SDK management takes place here, away from the instrumentation code, which should only access
  * the OpenTelemetry APIs.
  */
-public class ExampleConfiguration {
+public final class ExampleConfiguration {
 
   /**
    * Adds a BatchSpanProcessor initialized with OtlpGrpcSpanExporter to the TracerSdkProvider.

examples/otlp/src/main/java/io/opentelemetry/example/otlp/OtlpExporterExample.java

@@ -20,7 +20,7 @@ import io.opentelemetry.context.Scope;
  * default port. There is a docker-compose configuration for doing this in the docker subdirectory
  * of this module.
  */
-public class OtlpExporterExample {
+public final class OtlpExporterExample {
 
   public static void main(String[] args) throws InterruptedException {
     // this will make sure that a proper service.name attribute is set on all the spans/metrics.

examples/prometheus/src/main/java/io/opentelemetry/example/prometheus/ExampleConfiguration.java

@@ -11,7 +11,7 @@ import io.opentelemetry.sdk.metrics.SdkMeterProvider;
 import io.prometheus.client.exporter.HTTPServer;
 import java.io.IOException;
 
-public class ExampleConfiguration {
+public final class ExampleConfiguration {
   private static HTTPServer server;
 
   /**

examples/prometheus/src/main/java/io/opentelemetry/example/prometheus/PrometheusExample.java

@@ -17,7 +17,7 @@ import java.util.concurrent.ThreadLocalRandom;
  * awaiting processing. The {@link LongValueObserver} Updater gets executed every collection
  * interval.
  */
-public class PrometheusExample {
+public final class PrometheusExample {
   private long incomingMessageCount;
 
   public PrometheusExample(MeterProvider meterProvider) {

examples/sdk-usage/src/main/java/io/opentelemetry/sdk/example/ConfigureSpanProcessorExample.java

@@ -15,7 +15,7 @@ import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
 import java.util.concurrent.TimeUnit;
 
 /** This example shows how to instantiate different Span Processors. */
-public class ConfigureSpanProcessorExample {
+public final class ConfigureSpanProcessorExample {
 
   private static final LoggingSpanExporter exporter = new LoggingSpanExporter();
   private static final OpenTelemetrySdk openTelemetry = OpenTelemetrySdk.builder().build();

examples/zipkin/src/main/java/io/opentelemetry/example/zipkin/ExampleConfiguration.java

@@ -18,7 +18,7 @@ import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
  * All SDK management takes place here, away from the instrumentation code, which should only access
  * the OpenTelemetry APIs.
  */
-public class ExampleConfiguration {
+public final class ExampleConfiguration {
   // Zipkin API Endpoints for uploading spans
   private static final String ENDPOINT_V2_SPANS = "/api/v2/spans";
 

examples/zipkin/src/main/java/io/opentelemetry/example/zipkin/ZipkinExample.java

@@ -6,7 +6,7 @@ import io.opentelemetry.api.trace.Tracer;
 import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.context.Scope;
 
-public class ZipkinExample {
+public final class ZipkinExample {
   // The Tracer we'll use for the example
   private final Tracer tracer;