fix #1036 Remove erroneous public scope from 3 internal operator classes

FluxDelaySequence, FluxIndex and FluxIndexFuseable are internal
implementations and should have been package-private instead of public.

build.gradle

@@ -273,6 +273,8 @@ project('reactor-core') {
 
 	//TODO after a release, bump the gradle.properties baseline
 	//TODO after a release, remove the reactor-core exclusions below if any
+	//gh-1036
+	classExcludes = ['reactor.core.publisher.FluxIndex', 'reactor.core.publisher.FluxIndexFuseable', 'reactor.core.publisher.FluxDelaySequence']
   }
 
   javadoc {

reactor-core/src/main/java/reactor/core/publisher/FluxDelaySequence.java

@@ -28,12 +28,12 @@
  * @author Simon Baslé
  */
 //adapted from RxJava2 FlowableDelay: https://github.com/ReactiveX/RxJava/blob/2.x/src/main/java/io/reactivex/internal/operators/flowable/FlowableDelay.java
-public final class FluxDelaySequence<T> extends FluxOperator<T, T> {
+final class FluxDelaySequence<T> extends FluxOperator<T, T> {
 
 	final Duration  delay;
 	final Scheduler scheduler;
 
-	public FluxDelaySequence(Flux<T> source, Duration delay, Scheduler scheduler) {
+	FluxDelaySequence(Flux<T> source, Duration delay, Scheduler scheduler) {
 		super(source);
 		this.delay = delay;
 		this.scheduler = scheduler;

reactor-core/src/main/java/reactor/core/publisher/FluxIndex.java

@@ -34,7 +34,7 @@
  *
  * @author Simon Baslé
  */
-public class FluxIndex<T, I> extends FluxOperator<T, I> {
+final class FluxIndex<T, I> extends FluxOperator<T, I> {
 
 	private final BiFunction<? super Long, ? super T, ? extends I> indexMapper;
 

reactor-core/src/main/java/reactor/core/publisher/FluxIndexFuseable.java

@@ -51,7 +51,7 @@
  *
  * @author Simon Baslé
  */
-public class FluxIndexFuseable<T, I> extends FluxOperator<T, I>
+final class FluxIndexFuseable<T, I> extends FluxOperator<T, I>
 		implements Fuseable {
 
 	private final BiFunction<? super Long, ? super T, ? extends I> indexMapper;