hide Publisher and Subscriber's getStats() (#1555)

* hide Publisher and Subscriber's getStats()

The methods are not yet implemented,
so there is no reason to expose it.
Another way out is to delete it for the time being.

* delete the methods

Author: pongad

google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Publisher.java

@@ -468,12 +468,6 @@ public boolean failOnFlowControlLimits() {
     return failOnFlowControlLimits;
   }
 
-  /** Retrieves a snapshot of the publisher current {@link PublisherStats statistics}. */
-  public PublisherStats getStats() {
-    // TODO: Implement this.
-    throw new UnsupportedOperationException();
-  }
-
   /**
    * Schedules immediate publishing of any outstanding messages and waits until all are processed.
    *

google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PublisherStats.java

@@ -23,7 +23,7 @@
  * Publisher}.
  */
 @AutoValue
-public abstract class PublisherStats {
+abstract class PublisherStats {
   /** Number of successfully published messages. */
   public abstract long getAckedMessages();
 

google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java

@@ -365,11 +365,6 @@ public void run() {
     }
   }
 
-  public SubscriberStats getStats() {
-    // TODO: Implement me
-    return null;
-  }
-
   /** Subscription which the subscriber is subscribed to. */
   public String getSubscription() {
     return subscription;

google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/SubscriberStats.java

@@ -23,8 +23,8 @@
  * Subscriber}.
  */
 @AutoValue
-public abstract class SubscriberStats {
-  
+abstract class SubscriberStats {
+
   @AutoValue
   //TODO: Finish implementation.
   public abstract static class Stats {}