diff --git a/broker/src/main/java/io/moquette/broker/MemorySubscriptionsRepository.java b/broker/src/main/java/io/moquette/broker/MemorySubscriptionsRepository.java
index 94bd7212..ced9d784 100644
--- a/broker/src/main/java/io/moquette/broker/MemorySubscriptionsRepository.java
+++ b/broker/src/main/java/io/moquette/broker/MemorySubscriptionsRepository.java
@@ -2,13 +2,14 @@ package io.moquette.broker;
 
 import io.moquette.spi.impl.subscriptions.Subscription;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 
 public class MemorySubscriptionsRepository implements ISubscriptionsRepository {
 
-    private final List<Subscription> subscriptions = new LinkedList<>();
+    private final List<Subscription> subscriptions = new ArrayList<>();
 
     @Override
     public List<Subscription> listAllSubscriptions() {
diff --git a/broker/src/main/java/io/moquette/broker/Session.java b/broker/src/main/java/io/moquette/broker/Session.java
index 29a62ea2..5a13ff8e 100644
--- a/broker/src/main/java/io/moquette/broker/Session.java
+++ b/broker/src/main/java/io/moquette/broker/Session.java
@@ -20,7 +20,7 @@ class Session {
     private static final int FLIGHT_BEFORE_RESEND_MS = 5_000;
     private static final int INFLIGHT_WINDOW_SIZE = 10;
 
-    class InFlightPacket implements Delayed {
+    static class InFlightPacket implements Delayed {
 
         final int packetId;
         private long startTime;
diff --git a/broker/src/main/java/io/moquette/server/netty/AutoFlushHandler.java b/broker/src/main/java/io/moquette/server/netty/AutoFlushHandler.java
index e2ef93c8..75af863c 100644
--- a/broker/src/main/java/io/moquette/server/netty/AutoFlushHandler.java
+++ b/broker/src/main/java/io/moquette/server/netty/AutoFlushHandler.java
@@ -49,7 +49,7 @@ public class AutoFlushHandler extends ChannelDuplexHandler {
     }
 
     @Override
-    public void handlerAdded(ChannelHandlerContext ctx) {
+    public void handlerAdded(ChannelHandlerContext ctx) throws Exception  {
         if (ctx.channel().isActive() && ctx.channel().isRegistered()) {
             // channelActive() event has been fired already, which means this.channelActive() will
             // not be invoked. We have to initialize here instead.
@@ -141,10 +141,8 @@ public class AutoFlushHandler extends ChannelDuplexHandler {
      *
      * @param ctx
      *            the channel context.
-     * @throws Exception
-     *             in case of any IO error.
      */
-    protected void channelIdle(ChannelHandlerContext ctx/* , IdleStateEvent evt */) {
+    private void channelIdle(ChannelHandlerContext ctx) {
         // ctx.fireUserEventTriggered(evt);
         if (LOG.isDebugEnabled()) {
             LOG.debug("Flushing idle Netty channel {} Cid: {}", ctx.channel(), NettyUtils.clientID(ctx.channel()));