make SP to not validate logout responses

[ignasr at vault13.lt]

Hello all,

is it possible to make Shibboleth 2.5.0 SP not require logout responses 
to be signed?

IdP is SimpleSAMLphp, and I get errors:

***
opensaml::SecurityPolicyException at 
(https://my.domain/Shibboleth.sso/SLO/Redirect)
Security of LogoutResponse not established.
***

wiki didn't help. I have found lots of threads talking about problems 
with SLO, but haven't succeeded if finding one with a specific 
configuration option to turn validation off.

If there isn't one, what's the best way to hide this error from users?

Thank you,
IgnasR