Information
Preventing the root user from owning files in the ${wlp.install.dir} directory prevents unauthorized commands or files from being run.
When directories or files are owned by the root user, administration of those files requires a user to log in as root or elevate their existing login to have root privileges. Performing operations as the root user could result in unauthorized commands that could alter files beyond the scope of WebSphere Liberty itself.
Solution
Set the ownership and group of ${wlp.install.dir} to something other than root :
chown -R <non-root user>:<non-root group> ${wlp.install.dir}