data: mark constructor explicit

refs #4164

Change-Id: I4c723606643d88abe48ea540a554b9ef36a59808
diff --git a/src/data.hpp b/src/data.hpp
index 8f55ca2..eedea7a 100644
--- a/src/data.hpp
+++ b/src/data.hpp
@@ -49,6 +49,7 @@
    *  @warning In certain contexts that use Data::shared_from_this(), Data must be created
    *           using `make_shared`. Otherwise, .shared_from_this() will trigger undefined behavior.
    */
+  explicit
   Data(const Name& name = Name());
 
   /** @brief Create from wire encoding