define userName variable distinct from eppn

uw-spring-security-core/src/main/java/edu/wisc/uwss/preauth/FederatedPreauthenticatedUserDetailsAttributeMapper.java

@@ -57,13 +57,15 @@ public class FederatedPreauthenticatedUserDetailsAttributeMapper implements Prea
         }
         String pvi = request.getHeader(pviHeader);
         String cn = request.getHeader(fullNameHeader);
+        String userName = request.getHeader(usernameHeader);
+
         Collection<String> uddsMembership = new ArrayList<>();
         Enumeration<String> uddsHeaders = request.getHeaders(uddsHeader);
         if(uddsHeaders != null) {
             uddsMembership = Collections.list(uddsHeaders);
         }
         String email = request.getHeader(emailAddressHeader);
-        UWUserDetailsImpl result = new UWUserDetailsImpl(pvi, eppn, "", cn, email, uddsMembership);
+        UWUserDetailsImpl result = new UWUserDetailsImpl(pvi, userName, "", cn, email, uddsMembership);
         result.setSource("edu.wisc.uwss.preauth.federation");
         result.setEppn(eppn);
         result.setFirstName(request.getHeader(firstNameHeader));