Remove beast::Journal default constructor

src/ripple/resource/impl/ResourceManager.cpp

@@ -22,6 +22,7 @@
 #include <ripple/basics/chrono.h>
 #include <ripple/basics/Log.h>
 #include <ripple/beast/core/CurrentThreadName.h>
+#include <boost/core/ignore_unused.hpp>
 #include <condition_variable>
 #include <memory>
 #include <mutex>
@@ -45,6 +46,7 @@ public:
         : journal_ (journal)
         , logic_ (collector, stopwatch(), journal)
     {
+        boost::ignore_unused (journal_); // Keep unused journal_ just in case.
         thread_ = std::thread {&ManagerImp::run, this};
     }