When invalidating the session make it possible to start using a new one

Fix an issue where logout would correctly invalidate the session, but the
Context.session remained the invalidated one so any subsequent changes to
session values during that response would be lost. This change clears
Context.session so a new session is created as needed and available for use
during this response, instead of needing to wait for a subsequent request
for the new session to be available.

Author: Keith R. Gustafson

gemini/src/main/java/com/techempower/gemini/Context.java

@@ -386,6 +386,20 @@ public Session getSession(boolean create)
     return this.session;
   }
 
+  /**
+   * In addition to invalidating the session, also sets the Context.session member variable to null
+   * so it is re-created as needed and is available for immediate use.
+   */
+  public void invalidateSession()
+  {
+    if (this.session != null)
+    {
+      this.session.invalidate();
+    }
+    // Rely on getSession() to create a new session as needed.
+    this.session = null;
+  }
+
   /**
    * Gets the full standard (non-secure) URL to the Servlet.
    */

gemini/src/main/java/com/techempower/gemini/context/SessionNamedValues.java

@@ -306,11 +306,7 @@ public SessionNamedValues clear()
    */
   public SessionNamedValues invalidate()
   {
-    final Session session = context.getSession(false);
-    if (session != null)
-    {
-      session.invalidate();
-    }
+    context.invalidateSession();
     return this;
   }