Correct small grammar error in comment.

examples/src/main/java/io/grpc/examples/helloworld/HelloWorldServer.java

@@ -24,7 +24,7 @@ public class HelloWorldServer {
     Runtime.getRuntime().addShutdownHook(new Thread() {
       @Override
       public void run() {
-        // Use stderr here since the logger may has been reset by its JVM shutdown hook.
+        // Use stderr here since the logger may have been reset by its JVM shutdown hook.
         System.err.println("*** shutting down gRPC server since JVM is shutting down");
         HelloWorldServer.this.stop();
         System.err.println("*** server shut down");