add listener for session changes to ensure the cache is updated as th…

…e scope entries change

src/main/java/ortus/boxlang/runtime/application/Session.java

@@ -108,6 +108,10 @@ public SessionScope getSessionScope() {
 		return sessionScope;
 	}
 
+	public Application getApplication() {
+		return this.application;
+	}
+
 	public void shutdown() {
 		// Any buffer output in this context will be discarded
 		if ( startingListener != null ) {

src/main/java/ortus/boxlang/runtime/types/listeners/SessionListener.java

@@ -0,0 +1,28 @@
+package ortus.boxlang.runtime.types.listeners;
+
+import ortus.boxlang.runtime.application.Session;
+import ortus.boxlang.runtime.scopes.Key;
+
+public class SessionListener {
+
+	private final Session session;
+
+	public SessionListener( Session session ) {
+		this.session = session;
+	}
+
+	/**
+	 * Call when a value is being changed in an IListenable
+	 *
+	 * @param key      The key of the value being changed. For arrays, the key will be 1-based
+	 * @param newValue The new value (null if being removed)
+	 * @param oldValue The old value (null if being added)
+	 *
+	 * @return The new value to be set (you can override)
+	 */
+	public Object notify( Key key, Object newValue, Object oldValue ) {
+		this.session.getApplication().getSessionsCache().set( this.session.getID().getName(), this.session );
+		return null;
+	}
+
+}