[keycloak-user] getting resource owner and loggedin (identity) user attributes in evaluation context

[Suresh Mali]

Each user has one or more resource e.g. 'account'
Each user is assigned one or more  agents.  (agent is different user in the system with role agent)
I have added them in user attributes e.g let us say  there is user_a   who has account resource
there are users with agent roles  say  'agent_a', 'agent_b', 'agent_c'
In user_a  is attribute  I have added attribute
allowed_agents =  [ 'agent_a' ,'agent_b']
in agent_a & agent_b  have attibutes 
allowed_users =  ['user_a'] Now in policy evaluation   I want to ensure when agent_a & agent_b  try to access resource owned by user_a  they are allowed while agent_c is not allowed
how do I access resource owners  attributes  and  or  identity ownes attributes
I want to write a evaluation like something like this 
is it possible to get $permission.resource.owner.attributes["allowed_agent"]to return ['agent_a','agent_b']or $identity.attributes['allowed_users']  to return ['user_a']   so that I can evaluate the match
something like beowrule "Authorize Resource Owner" 
    dialect "mvel" 
    when 
       $evaluation : Evaluation( 
           $identity: context.identity, 
           $permission: permission, 
           $permission.resource.owner.attribute['allowed_agents'].indexOf($identity.id)
       ) 
    then 
        $evaluation.grant(); 
end