v0.2.55..v0.2.56 changeset ElementHashVisitor.h

diff --git a/hoot-core/src/main/cpp/hoot/core/visitors/ElementHashVisitor.h b/hoot-core/src/main/cpp/hoot/core/visitors/ElementHashVisitor.h
index acc348e..fb1885d 100644
--- a/hoot-core/src/main/cpp/hoot/core/visitors/ElementHashVisitor.h
+++ b/hoot-core/src/main/cpp/hoot/core/visitors/ElementHashVisitor.h
@@ -54,6 +54,7 @@ public:
   static std::string className() { return "hoot::ElementHashVisitor"; }
 
   ElementHashVisitor();
+  virtual ~ElementHashVisitor() = default;
 
   virtual void visit(const ElementPtr &e);