in src/main/java/org/apache/sling/servlethelpers/MockSlingHttpServletRequest.java [893:910]
public Principal getUserPrincipal() {
Principal principal = null;
// always return null for anonymous user
final String userid = getRemoteUser();
if (userid != null) {
ResourceResolver rr = getResourceResolver();
if (rr != null) {
principal = rr.adaptTo(Principal.class);
}
if (principal == null) {
// fallback to the userid
principal = () -> userid;
}
}
return principal;
}