[#1836] Add comment to explain why read is triggered

transport/src/main/java/io/netty/channel/nio/NioEventLoop.java

@@ -474,6 +474,8 @@ public final class NioEventLoop extends SingleThreadEventLoop {
 
         try {
             int readyOps = k.readyOps();
+            // Also check for readOps of 0 to workaround possible JDK bug which may otherwise lead
+            // to a spin loop
             if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
                 unsafe.read();
                 if (!ch.isOpen()) {