Hide the non-public APIs

src/main/java/net/jodah/recurrent/CompletableFuture.java

@@ -29,7 +29,7 @@ void setFuture(Future<T> delegate) {
     this.delegate = delegate;
   }
 
-  public void complete(T result, Throwable failure) {
+  void complete(T result, Throwable failure) {
     this.result = result;
     this.failure = failure;
     done = true;

src/main/java/net/jodah/recurrent/Invocation.java

@@ -12,7 +12,7 @@
  * @author Jonathan Halterman
  * @param <T> invocation result type
  */
-public class Invocation {
+class Invocation {
   private RetryPolicy retryPolicy;
   private Callable<?> callable;
   private ScheduledExecutorService executor;