Resolution: TIBCO ActiveMatrix BusinessWorks Plug-in for sFTP is used to securely transfer files. The sFTP plugin uses Jsch 0.1.51, which supports both ssh-dss and ssh-rsa. If you need to configure the SFTP server to use a DSA key instead of the default (stronger) RSA keys, the SFTP server needs to be configured to use the DSA key.
There are ways to configure the SFTP server to use the DSA as a server host key, such as using the HostKeyAlgorithms parameter. Once the sFTP server has been reconfigured, when regenerating the known host file it will contain DSA keys.