Exception in thread "main" java.lang.NoClassDefFoundError: HashtableMap
	at DijkstraGraph.<init>(DijkstraGraph.java:65)
	at WebApp.createWorkingFrontend(WebApp.java:114)
	at WebApp.handleSingleResponse(WebApp.java:173)
	at WebApp.main(WebApp.java:47)
Caused by: java.lang.ClassNotFoundException: HashtableMap
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
	... 4 more