deprecate no longer required concat_alternatives

See merge request !1513

GaudiExamples/src/FunctionalAlgorithms/selector.cpp

@@ -20,9 +20,7 @@ namespace Gaudi {
         : public Functional::FilterPredicate<bool( const Gaudi::Range_<Gaudi::Examples::MyTrack::ConstVector>& )> {
     public:
       CountSelectedTracks( const std::string& name, ISvcLocator* pSvc )
-          : FilterPredicate( name, pSvc,
-                             { KeyValue{ "InputData", Functional::concat_alternatives( "BogusLocation", "MoreBogus",
-                                                                                       "MyOutTracks" ) } } ) {}
+          : FilterPredicate( name, pSvc, { KeyValue{ "InputData", "MyOutTracks" } } ) {}
 
       StatusCode initialize() override {
         StatusCode sc = FilterPredicate::initialize();

GaudiFunctional/include/Gaudi/Functional/utilities.h

@@ -19,13 +19,13 @@
 namespace Gaudi::Functional {
 
   // This utility is needed when the inputs of a functional algorithm may be stored in several locations
-  inline std::string concat_alternatives( std::initializer_list<std::string> c ) {
+  [[deprecated]] inline std::string concat_alternatives( std::initializer_list<std::string> c ) {
     return boost::algorithm::join( c, ":" );
   }
 
   template <typename... Strings>
-  std::string concat_alternatives( const Strings&... s ) {
-    return concat_alternatives( std::initializer_list<std::string>{ s... } );
+  [[deprecated]] std::string concat_alternatives( const Strings&... s ) {
+    return boost::algorithm::join( std::initializer_list<std::string>{ s... }, ":" );
   }
 
   [[deprecated( "please use `updateHandleLocation` instead of `Gaudi::Functional::updateHandleLocation`" )]] inline void