Fix for - NPE in SessionHandlerValve.java accessing Tomcat's /manager app

src/main/java/tomcat/request/session/redis/SessionHandlerValve.java

@@ -31,7 +31,9 @@ public class SessionHandlerValve extends ValveBase {
             LOGGER.error("Error processing request", ex);
             throw new BackendException();
         } finally {
+            if (this.manager != null) {
                 this.manager.afterRequest();
             }
         }
     }
+}

src/main/java/tomcat/request/session/redis/SingleSignOnValve.java

@@ -225,8 +225,10 @@ public class SingleSignOnValve extends SingleSignOn {
 
     /** To set session manager. */
     void setSessionManager(Manager manager) {
+        if (manager != null) {
             this.manager = (SessionManager) manager;
         }
+    }
 
     /** To expire session. */
     private void expire(SingleSignOnSessionKey key) {