Fix warnings, reduce visibility if possible

reactor/src/main/java/com/hivemq/client2/internal/mqtt/reactor/MqttReactorClient.java

@@ -167,7 +167,7 @@ public MqttReactorClient(final @NotNull Mqtt5RxClient delegate) {
         return delegate.toBlocking();
     }
 
-    private class MqttSubscribePublishesBuilder
+    public class MqttSubscribePublishesBuilder
             extends MqttSubscribeBuilder.Publishes<FluxWithSingle<Mqtt5Publish, Mqtt5SubAck>> {
 
         @Override

reactor/src/main/java/com/hivemq/client2/internal/mqtt/reactor/mqtt3/Mqtt3ReactorClientView.java

@@ -149,7 +149,7 @@ public Mqtt3ReactorClientView(final @NotNull Mqtt3RxClient delegate) {
         return delegate.toBlocking();
     }
 
-    private class Mqtt3SubscribeViewPublishesBuilder
+    public class Mqtt3SubscribeViewPublishesBuilder
             extends Mqtt3SubscribeViewBuilder.Publishes<FluxWithSingle<Mqtt3Publish, Mqtt3SubAck>> {
 
         @Override

src/main/java/com/hivemq/client2/internal/mqtt/MqttAsyncClient.java

@@ -310,7 +310,7 @@ public void onComplete() {}
         public void onError(final @NotNull Throwable t) {}
     }
 
-    private class SubscribeBuilder extends MqttSubscribeBuilder<SubscribeBuilder>
+    public class SubscribeBuilder extends MqttSubscribeBuilder<SubscribeBuilder>
             implements Mqtt5AsyncClient.SubscribeBuilder.Start.Complete,
             Mqtt5AsyncClient.SubscribeBuilder.AfterCallback {
 

src/main/java/com/hivemq/client2/internal/mqtt/MqttBlockingClient.java

@@ -216,7 +216,7 @@ public void disconnect(final @NotNull Mqtt5Disconnect disconnect) {
         return delegate.toAsync();
     }
 
-    private static class Publishes implements Mqtt5BlockingClient.Publishes, FlowableSubscriber<Mqtt5Publish> {
+    public static class Publishes implements Mqtt5BlockingClient.Publishes, FlowableSubscriber<Mqtt5Publish> {
 
         private final @NotNull AtomicReference<@Nullable Subscription> subscription = new AtomicReference<>();
         private final @NotNull NodeList<Entry> entries = new NodeList<>();

src/main/java/com/hivemq/client2/internal/mqtt/MqttRxClient.java

@@ -270,7 +270,7 @@ public MqttRxClient(final @NotNull MqttClientConfig clientConfig) {
         return new MqttBlockingClient(this);
     }
 
-    private class MqttSubscribePublishesBuilder
+    public class MqttSubscribePublishesBuilder
             extends MqttSubscribeBuilder.Publishes<FlowableWithSingle<Mqtt5Publish, Mqtt5SubAck>> {
 
         @Override

src/main/java/com/hivemq/client2/internal/mqtt/handler/auth/MqttReAuthHandler.java

@@ -44,7 +44,7 @@
  * @author Silvio Giebl
  */
 @ConnectionScope
-public class MqttReAuthHandler extends AbstractMqttAuthHandler {
+class MqttReAuthHandler extends AbstractMqttAuthHandler {
 
     private @Nullable CompletableFlow flow;
 

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/incoming/MqttSubscribedPublishFlowTree.java

@@ -36,7 +36,7 @@
  * @author Silvio Giebl
  */
 @NotThreadSafe
-public class MqttSubscribedPublishFlowTree implements MqttSubscribedPublishFlows {
+class MqttSubscribedPublishFlowTree implements MqttSubscribedPublishFlows {
 
     private @Nullable TopicTreeNode rootNode;
 

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/incoming/MqttSubscribedPublishFlows.java

@@ -29,7 +29,7 @@
  * @author Silvio Giebl
  */
 @NotThreadSafe
-public interface MqttSubscribedPublishFlows {
+interface MqttSubscribedPublishFlows {
 
     void subscribe(
             @NotNull MqttSubscription subscription,

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/outgoing/MqttOutgoingQosHandler.java

@@ -173,7 +173,7 @@ void request(final long n) {
             this.shrinkRequests = 0;
             subscription.request(n - shrinkRequests);
         } else {
-            this.shrinkRequests -= n;
+            this.shrinkRequests = shrinkRequests - (int) n;
         }
     }
 

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/outgoing/MqttPublishFlowableAckLink.java

@@ -32,7 +32,7 @@
 /**
  * @author Silvio Giebl
  */
-public class MqttPublishFlowableAckLink extends Flowable<MqttPublishWithFlow> {
+class MqttPublishFlowableAckLink extends Flowable<MqttPublishWithFlow> {
 
     private final @NotNull Flowable<MqttPublish> source;
     private final @NotNull MqttAckFlowableFlow ackFlow;

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/outgoing/MqttPublishFlowables.java

@@ -30,7 +30,7 @@
  * @author Silvio Giebl
  */
 @ClientScope
-public class MqttPublishFlowables extends Flowable<Flowable<MqttPublishWithFlow>> implements Subscription {
+class MqttPublishFlowables extends Flowable<Flowable<MqttPublishWithFlow>> implements Subscription {
 
     private static final @NotNull InternalLogger LOGGER = InternalLoggerFactory.getLogger(MqttPublishFlowables.class);
 

src/main/java/com/hivemq/client2/internal/mqtt/handler/publish/outgoing/MqttPublishWithFlow.java

@@ -22,7 +22,7 @@
 /**
  * @author Silvio Giebl
  */
-class MqttPublishWithFlow extends MqttPubOrRelWithFlow {
+public class MqttPublishWithFlow extends MqttPubOrRelWithFlow {
 
     private final @NotNull MqttPublish publish;
 

src/main/java/com/hivemq/client2/internal/mqtt/handler/subscribe/MqttSubscriptionHandler.java

@@ -130,7 +130,7 @@ public void subscribe(
         });
     }
 
-    public void unsubscribe(
+    void unsubscribe(
             final @NotNull MqttUnsubscribe unsubscribe, final @NotNull MqttSubOrUnsubAckFlow<MqttUnsubAck> flow) {
 
         flow.getEventLoop().execute(() -> {

src/main/java/com/hivemq/client2/internal/mqtt/message/subscribe/MqttSubscription.java

@@ -116,14 +116,14 @@ public int hashCode() {
 
     public byte encodeSubscriptionOptions() {
         byte subscriptionOptions = 0;
-        subscriptionOptions |= retainHandling.getCode() << 4;
+        subscriptionOptions |= (byte) (retainHandling.getCode() << 4);
         if (retainAsPublished) {
             subscriptionOptions |= 0b0000_1000;
         }
         if (noLocal) {
             subscriptionOptions |= 0b0000_0100;
         }
-        subscriptionOptions |= maxQos.getCode();
+        subscriptionOptions |= (byte) maxQos.getCode();
         return subscriptionOptions;
     }
 

src/main/java/com/hivemq/client2/internal/mqtt/mqtt3/Mqtt3AsyncClientView.java

@@ -277,7 +277,7 @@ public void publishes(
         return new Mqtt3BlockingClientView(delegate.toBlocking());
     }
 
-    private class SubscribeViewBuilder extends Mqtt3SubscribeViewBuilder<SubscribeViewBuilder>
+    public class SubscribeViewBuilder extends Mqtt3SubscribeViewBuilder<SubscribeViewBuilder>
             implements SubscribeBuilder.Start.Complete, SubscribeBuilder.AfterCallback {
 
         private @Nullable Consumer<Mqtt3Publish> callback;

src/main/java/com/hivemq/client2/internal/mqtt/mqtt3/Mqtt3BlockingClientView.java

@@ -173,7 +173,7 @@ public void disconnect() {
         return new Mqtt3AsyncClientView(delegate.toAsync());
     }
 
-    private static class PublishesView implements Publishes {
+    public static class PublishesView implements Publishes {
 
         private final @NotNull Mqtt5BlockingClient.Publishes delegate;
 

src/main/java/com/hivemq/client2/internal/mqtt/mqtt3/Mqtt3RxClientView.java

@@ -207,7 +207,7 @@ public class Mqtt3RxClientView implements Mqtt3RxClient {
         return new Mqtt3BlockingClientView(delegate.toBlocking());
     }
 
-    private class Mqtt3SubscribeViewPublishesBuilder
+    public class Mqtt3SubscribeViewPublishesBuilder
             extends Mqtt3SubscribeViewBuilder.Publishes<FlowableWithSingle<Mqtt3Publish, Mqtt3SubAck>> {
 
         @Override