offer.java

public void createOffer(){
        
        peerConnection.createOffer(new CustomSdpObserver(){

            @Override
            public void onCreateSuccess(SessionDescription sessionDescription) {
                super.onCreateSuccess(sessionDescription);
                
                peerConnection.setLocalDescription(new CustomSdpObserver(), sessionDescription);
                // sessionDescription.description is string which needs to the shared across network
            }

            @Override
            public void onCreateFailure(String s) {
                super.onCreateFailure(s);
                // Offer creation failed
            }
        }, new MediaConstraints());
    }