in src/main/java/org/apache/sling/jcr/filetransfer/sftp/internal/SftpService.java [85:93]
private SshServer sshServer() {
final SshServer sshServer = SshServer.setUpDefaultServer();
sshServer.setPort(configuration.ssh_server_port());
sshServer.setPasswordAuthenticator(passwordAuthenticator);
sshServer.setKeyPairProvider(keyPairProvider);
sshServer.setSubsystemFactories(Collections.singletonList(sftpSubsystemFactory));
sshServer.setFileSystemFactory(fileSystemFactory);
return sshServer;
}