v0.2.55..v0.2.56 changeset MultiVisitor.h

diff --git a/hoot-core/src/main/cpp/hoot/core/visitors/MultiVisitor.h b/hoot-core/src/main/cpp/hoot/core/visitors/MultiVisitor.h
index b45e56d..ac9a353 100644
--- a/hoot-core/src/main/cpp/hoot/core/visitors/MultiVisitor.h
+++ b/hoot-core/src/main/cpp/hoot/core/visitors/MultiVisitor.h
@@ -40,7 +40,8 @@ public:
 
   static std::string className() { return "hoot::MultiVisitor"; }
 
-  MultiVisitor();
+  MultiVisitor() = default;
+  virtual ~MultiVisitor() = default;
 
   virtual void visit(const std::shared_ptr<Element>& e);