Merge "OAuth: Check for session validity during logout" into stable-2.10

gerrit-oauth/src/main/java/com/google/gerrit/httpd/auth/oauth/OAuthLogoutServlet.java

diff --git a/gerrit-oauth/src/main/java/com/google/gerrit/httpd/auth/oauth/OAuthLogoutServlet.java b/gerrit-oauth/src/main/java/com/google/gerrit/httpd/auth/oauth/OAuthLogoutServlet.java
index 43b85bd..35253a1 100644
--- a/gerrit-oauth/src/main/java/com/google/gerrit/httpd/auth/oauth/OAuthLogoutServlet.java
+++ b/gerrit-oauth/src/main/java/com/google/gerrit/httpd/auth/oauth/OAuthLogoutServlet.java
@@ -52,6 +52,8 @@
   protected void doLogout(HttpServletRequest req, HttpServletResponse rsp)
       throws IOException {
     super.doLogout(req, rsp);
-    oauthSession.get().logout();
+    if (req.getSession(false) != null) {
+      oauthSession.get().logout();
+    }
   }
 }