Add HTTP headers to Meteor's whitelist

I have a Meteor application deployed behind Apache, which is acting
as a proxy and authenticates the user via SSO. I have the following
piece of code:

Meteor.onConnection(connection => console.log(connection.httpHeaders))

Apache sends the HTTP header REMOTE_USER but I cannot see the
information in Meteor’s server-side. I did some research and found out
that Meteor whitelists the HTTP headers but it doesn’t say how to add to
the whitelist. Does anybody know?

Or is there another way of getting the information?