code: private void handleUserLogin(X509Certificate certChain[]) throws RegistryException, CertificateMapNotSupportedException, CertificateMapFailedException, EntryNotFoundException, Exception {
          UserRegistry userRegistry = getUserRegistry();
          username = userRegistry.mapCertificate(certChain);
          authenticatedId = userRegistry.getUniqueUserId(username);
          securityName = userRegistry.getUserSecurityName(authenticatedId);
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "username=[" + username +
                           "] authenticatedId=[" + authenticatedId +
                           "] securityName=[" + securityName + "]");
          }
          setUpTemporarySubject();
      }
docs: Handles a non-collective certificate login.
  
  Note:
  In distributed env, both username and securityName in this method are the same.
  In zOS env, username has platform cred appended while securityName does not.
  
  username : TESTUSER::c2c2c70001013....00
  securityName: TESTUSER
  
  @param certChain
  @throws RegistryException
  @throws CertificateMapNotSupportedException
  @throws CertificateMapFailedException
  @throws EntryNotFoundException
  @throws Exception