code review fix

Change-Id: Ie616543094aaa31d596980ba7a3cef05de4351fc
diff --git a/src/challenge/challenge-credential.hpp b/src/challenge/challenge-credential.hpp
index 7b48483..30fb933 100644
--- a/src/challenge/challenge-credential.hpp
+++ b/src/challenge/challenge-credential.hpp
@@ -61,7 +61,7 @@
 
   Block
   genChallengeRequestTLV(Status status, const std::string& challengeStatus,
-                         std::multimap<std::string, std::string>&& params) override;
+                         const std::multimap<std::string, std::string>& params) override;
 
   static void
   fulfillParameters(std::multimap<std::string, std::string>& params,