yep but it's public so it cannot be changed until the next major version. It can not be changed but we can add a new method and deprecate the old one... let me do in a few minutes  Fixed by https://github.com/netty/netty/pull/6910. Please check Fixed by https://github.com/netty/netty/pull/6910
Typo? EpollSocketChannelConfig.setTcpKeepCntl
https://github.com/netty/netty/blob/3cc405296310643bccddc8c81998c97f25b3201c/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java#L420

shouldn't it be called setTcpKeepCnt?
transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java
transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java
diff --git a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java
index 4ac335619b8..eaf2523b980 100644
--- a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java
+++ b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannelConfig.java
@@ -141,7 +141,7 @@ public <T> boolean setOption(ChannelOption<T> option, T value) {
         } else if (option == EpollChannelOption.TCP_KEEPIDLE) {
             setTcpKeepIdle((Integer) value);
         } else if (option == EpollChannelOption.TCP_KEEPCNT) {
-            setTcpKeepCntl((Integer) value);
+            setTcpKeepCnt((Integer) value);
         } else if (option == EpollChannelOption.TCP_KEEPINTVL) {
             setTcpKeepIntvl((Integer) value);
         } else if (option == EpollChannelOption.TCP_USER_TIMEOUT) {
@@ -415,9 +415,17 @@ public EpollSocketChannelConfig setTcpKeepIntvl(int seconds) {
     }
 
     /**
-     * Set the {@code TCP_KEEPCNT} option on the socket. See {@code man 7 tcp} for more details.
+     * @deprecated use {@link #setTcpKeepCnt(int)}
      */
+    @Deprecated
     public EpollSocketChannelConfig setTcpKeepCntl(int probes) {
+        return setTcpKeepCnt(probes);
+    }
+
+    /**
+     * Set the {@code TCP_KEEPCNT} option on the socket. See {@code man 7 tcp} for more details.
+     */
+    public EpollSocketChannelConfig setTcpKeepCnt(int probes) {
         try {
             channel.socket.setTcpKeepCnt(probes);
             return this;
