e4bacc3e92
Fixes https://github.com/spring-projects/spring-integration/issues/8708 According to the `org.apache.sshd.common.channel.ChannelAsyncOutputStream.writeBuffer()` JavaDocs cannot be used concurrently. * Introduce internal `DefaultSftpSessionFactory.ConcurrentSftpClient` extension of the `DefaultSftpClient` to set a `Lock` around `super.send(cmd, buffer);` * Remove lock from the `SftpSession` since it now is managed by the mentioned `ConcurrentSftpClient` **Cherry-pick to `6.1.x` & `6.0.x`**