req.getSession(false) had value just before redirection but is returning null after redirection from Weblogic 12.2.1.0.0. ServletResponseImpl.sendRedirect is removing session instance and sessionDestroyed method is not getting called.
This works fine in tomcat and older version of weblogic.
Please find below stack trace: weblogic.servlet.internal.ServletResponseImpl.sendRedirect(ServletResponseImpl.java:1027) at weblogic.servlet.internal.ServletResponseImpl.sendRedirect(ServletResponseImpl.java:948) at javax.servlet.http.HttpServletResponseWrapper.sendRedirect(HttpServletResponseWrapper.java:176)
There is no issue with the code.
This is a bug in Weblogic. Contact Weblogic team for the fix.