The whoami operation is not usable with the JMX integration.

[standalone@localhost:9990 /] :whoami(verbose=true)
{
    "outcome" => "success",
    "result" => {
        "identity" => {
            "username" => "darranl",
            "realm" => "ManagementRealm"
        },
        "groups" => [
            "One",
            "Two",
            "Three"
        ],
        "roles" => [
            "One",
            "Two",
            "Three"
        ]
    }
}