v0.2.55..v0.2.56 changeset BuildingLevelsVisitor.h

diff --git a/hoot-core/src/main/cpp/hoot/core/visitors/BuildingLevelsVisitor.h b/hoot-core/src/main/cpp/hoot/core/visitors/BuildingLevelsVisitor.h
index 8eb1e1e..8689369 100644
--- a/hoot-core/src/main/cpp/hoot/core/visitors/BuildingLevelsVisitor.h
+++ b/hoot-core/src/main/cpp/hoot/core/visitors/BuildingLevelsVisitor.h
@@ -47,6 +47,7 @@ public:
   static std::string className() { return "hoot::BuildingLevelsVisitor"; }
 
   BuildingLevelsVisitor();
+  virtual ~BuildingLevelsVisitor() = default;
 
   virtual void visit(const ConstElementPtr& e) override;