I'm probably answering my own question, but when I add multiple SSH keys for a host, it seems like it is only taking the last one added.
I'm doing something like this:
SecureFileTransferClient ftp = createFTPClient();
SSHFTPValidator ftpValidator = ftp.getAdvancedSSHSettings().getSSHServerValidator();
for( InputStream keyInputStream : getKeyInputStreams() )
ftpValidator.addKnownHost( "myHost", keyInputStream );
After the loop finishes, calling ftpValidator.getKnownHostKeys("myHost") always returns one key and it is the last key added. Each key being added is different.
I'm using version 4.7.0.