After creating a secure http-listener and installing lbplugin, the magnus.conf and obj.conf files under the webserver_instance_dir/config are getting modifiedand the lbplugin contents are getting removed.
The installer modifies the magnus.conf and obj.conf configuration files on the Application Server as part of the installation of the load balancer plugin. If you log in to the Application Server admin console and try to manage the instance configuration for the instance on which the load balancer has been installed, the Application Server gives a warning message stating that it has detected a manual edit in the configuration. This warning is in fact referring to the changes made by the installer.
Verify that the changes made by the installer have not been overwritten.