[keycloak-user] SAML Broker configuration based on SAML/Broker examples leads to client_not_found error

[Dmitry Korchemkin]

I was trying to set up two SAML keycloak idp's, based on basic SAML and
broker examples provided with keycloak.
Using broker example as a reference, i added an IDP to saml-demo client. In
this IDP i changed Single Sign-On Service URL to the uri of the second
realm - http://localhost:8080/auth/realms/saml-broker-realm/protocol/saml,
just like in the broker example.
In saml-broker-realm i configure SAML client identically to the broker
example.
When i try to log in using this new configuration by pressing a new button,
i get the following error: type=LOGIN_ERROR, realmId=saml-demo, clientId=
http://localhost:8080/auth/realms/saml-demo, userId=null,
ipAddress=10.0.2.2, error=client_not_found.

I tried googling the issue, but all the answers seem to be linked to
keycloak.json, which indeed is not used by SAML example, as far as i can
tell.
Am i right in my assumption that this configuration will not work by
definition due to keycloak.json missing, or this error may be caused by
something else?