Need help to connect SSH to second server from E2c server using JSch Java library?

Question

My scenario:

Step1:Connect to ec2 server using file ".pem"

-host: 52.194.228.89
-port: 22
-username: ec2-user
-File .pem for authorization

Step2: Continue connecting SSH to second server using following command:

Command line: ssh -i ~/.ssh/id_rsa linseed@10.231.14.139

-host: 10.231.14.137
-username: linseed
-password: linseed

=> For step1: I already connected to ec2 server using file .pem successfully. I using Java:

public static Session connectServerAwsOld(String host, int port, String userName, String filePemPath) {
        Session session;
        JSch jsch = new JSch();
       
        try {
            session = jsch.getSession(userName, host, port);    
            jsch.addIdentity("filePemPath");
            session.setConfig("StrictHostKeyChecking", "no");
            System.out.println("Establishing Connection...");
            session.connect();
            System.out.println("Connection established successfully.");

        } catch (JSchException e) {
            System.out.println("not connected server");
            session = null;
        }
        return session;
    }

Result:

Establishing Connection...
Connection established successfully.

=>For Step2: Currently i have not found out the way to implement connection yet like the way i did manually (Command line: ssh -i ~/.ssh/id_rsa linseed@10.231.14.139). Could someone help to take a look on my issue and give me a advice for implement connection? Thanks in advance you guys...