Why SSH_FXF_APPEND flag is commented out while calling the APPEND operation of JSCH

A quick brief, I am working with one of the implementations of SFTP server for .NET i.e. NSoftware IPWorks SSH. I wanted to deduce the APPEND operation invoked by the client and do some logic on that. I quickly implemented the SSH client using Renci's SSH.NET package and was able to deduce the APPEND operation on the SFTP server.

But, the thing turned sideways when I used JCraft's JSch a Java implementation of SSH2. When I invoked the APPEND operation using JSch, the bitmask which notifies the current operation being performed was different from what I was expecting. I was expecting the flag value as 14 which notifies the APPEND call but I got it as 10 which clearly messed up my logic.

Going through the implementation of APPEND call in JSch I found out that the SSH_FXF_APPEND bitmask is commented out and there's no explanation as well.

JSch Implementation

private void sendOPENA(byte[] path) throws Exception{
sendOPEN(path, SSH_FXF_WRITE|/*SSH_FXF_APPEND|*/SSH_FXF_CREAT);

}

According to SSH RFP below are the bitmask values for the operations. https://tools.ietf.org/html/draft-ietf-secsh-filexfer-04#page-17

#define SSH_FXF_READ            0x00000001
#define SSH_FXF_WRITE           0x00000002
#define SSH_FXF_APPEND          0x00000004
#define SSH_FXF_CREAT           0x00000008
#define SSH_FXF_TRUNC           0x00000010
#define SSH_FXF_EXCL            0x00000020
#define SSH_FXF_TEXT            0x00000040

Does someone know what is going on here because all implementations should be consistent with the RFP?