Thread on users@: "Regarding JSESSIONIDSSO Cookie maintained by tomcat"
http://tomcat.markmail.org/thread/y7m6ceiusm65p5bc

The code for clearing the cookie is in
o.a.catalina.authenticator.SingleSignOn.invoke(...)

[[[
            cookie.setMaxAge(0);
            response.addCookie(cookie);
]]]

The code for setting the cookie is in
o.a.catalina.authenticator.AuthenticatorBase.register(...)


I see the following issues with the code that clears the cookie in SingleSignOn.invoke():

1). The cookie value is echoed back.
To clear a cookie it should be enough to use any fixed value.

(OP concerns are that Secure and HttpOnly flags are not set on the Set-Cookie header. It should not be an issue, as the value is known to be invalid, and as browser is expected to immediately remove the cookie. Still I can agree that it is not pretty).

2) The Domain and Path attributes should have the same values as for a newly created SSO cookie.

(The new cookie replaces the old cookie if it has the same name, domain and path. - RFC 6265 page 24
- Chapter 5.3. Storage Model, item 11)


BTW, an unrelated issue:
The code in SingleSignOn.invoke() operates on the first SSO cookie that it finds. It does not expect browser to send several cookies with this name.