Multiple connection to remote sftp using same user throwing FileSystemAlreadyExistsException

### Description

We did the basic setup for apache mina sshd server and set the FileSystemFactory of sshd (Ex: sshd.setFileSystemFactory(new SftpClientFileSystemFactory());) to connect to remote sftp server. Its working fine with one connection but when we tried to attempt multiple connection using same user it throws FileSystemAlreadyExistsException.

Sample code from custom SftpClientFileSystemFactory

public class SftpClientFileSystemFactory implements FileSystemFactory {
private static final Logger logger = LoggerFactory.getLogger(SftpClientFileSystemFactory.class.getName());

public SftpClientFileSystemFactory() {
}

public Path getUserHomeDir(SessionContext session) throws IOException {
return null;
}

public FileSystem createFileSystem(SessionContext session) throws IOException {
String username = session.getUsername();
FileSystem fs = null;
URI uri = SftpFileSystemProvider.createFileSystemURI("sftp.remote.test", 2022, "user", "pass"); //Example
try {
fs = FileSystems.newFileSystem(uri, Collections.emptyMap());
} catch (IOException e) {
logger.error("An error occurred while creating the file system or walking the file tree", e);
}
return fs;
}
}

**sshd server config**
SshServer sshd = SshServer.setUpDefaultServer();
sshd.setPort(22);
sshd.setKeyPairProvider(new SimpleGeneratorHostKeyProvider());
sshd.setPasswordAuthenticator((username, password, session) -> {
return true;
});

sshd.setPublickeyAuthenticator((username, key, session) -> {
return true;
});
sshd.setFileSystemFactory(new SftpClientFileSystemFactory());
sshd.setSubsystemFactories(Arrays.asList(new SftpSubsystemFactory()));
sshd.start();

### Motivation

Wanted to check if this functionality exists or its not valid.

### Alternatives considered

_No response_

### Additional context

_No response_

Start with the custom SftpClientFileSystemFactory.createFileSystem method and the FileSystems.newFileSystem call using SftpFileSystemProvider.createFileSystemURI. Run the supplied setup with two sessions using the same user and inspect when FileSystemAlreadyExistsException is raised. Done means establishing whether multiple sessions are supported and documenting or reproducing the expected behavior clearly.

Written by the indexing model from the issue text.