Actually, the channel number is unsigned

Author: 0x6e6562

src/com/rabbitmq/client/impl/ChannelManager.java

@@ -98,8 +98,8 @@ public synchronized ChannelN createChannel(AMQConnection connection, int channel
 
     public synchronized int allocateChannelNumber(int maxChannels) {
         if (maxChannels == 0) {
-            // The framing encoding only allows for 16-bit integers for the channel number
-            maxChannels = Short.MAX_VALUE;
+            // The framing encoding only allows for unsigned 16-bit integers for the channel number
+            maxChannels = (1 << 16) - 1;
         }
         int channelNumber = -1;
         for (int candidate = 1; candidate <= maxChannels; candidate++) {