keystone/api-ref/source/v3-ext/samples/OS-TRUST/trust-create-request.json

{
    "trust": {
        "expires_at": "2013-02-27T18:30:59.999999Z",
        "impersonation": true,
        "allow_redelegation": true,
        "project_id": "ddef321",
        "roles": [
            {
                "name": "member"
            }
        ],
        "trustee_user_id": "86c0d5",
        "trustor_user_id": "a0fdfd"
    }
}