security: use exponential backoff in CertificateFetcherFromNetwork

refs: #4718, #4712

Change-Id: I8def533528b82ea00096e9d87897acf31dff24a4
diff --git a/src/security/v2/certificate-fetcher-offline.cpp b/src/security/v2/certificate-fetcher-offline.cpp
index 8bf28e1..a59c58b 100644
--- a/src/security/v2/certificate-fetcher-offline.cpp
+++ b/src/security/v2/certificate-fetcher-offline.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2017 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2018 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,7 +31,7 @@
                                    const ValidationContinuation& continueValidation)
 {
   state->fail({ValidationError::Code::CANNOT_RETRIEVE_CERT,
-               "Cannot fetch certificate " + certRequest->m_interest.getName().toUri() + " in offline mode"});
+               "Cannot fetch certificate " + certRequest->interest.getName().toUri() + " in offline mode"});
 }
 
 } // namespace v2