How to use nomad cli `-filter` argument to filter boolean values?

Dear Nomad community,

I am trying nomad cli and using filter argument to filter nomad nodes based on drain value.

$ nomad node status -filter "Drain == true"
Error querying node status: Unexpected response code: 400 (failed to read result page: error finding value in datum: /Drain at part 0: couldn't find key: struct field with name "Drain")
 09:17:50 ~
$ nomad node status -filter "Drain is true"
Error querying node status: Unexpected response code: 400 (failed to create result paginator: failed to read filter expression: 1:10 (9): no match found, expected: "empty", "not" or [ \t\r\n])
 09:17:53 ~
$ nomad node status -filter "Drain is True"
Error querying node status: Unexpected response code: 400 (failed to create result paginator: failed to read filter expression: 1:10 (9): no match found, expected: "empty", "not" or [ \t\r\n])
 09:17:59 ~
$ nomad node status -filter "Drain == True"
Error querying node status: Unexpected response code: 400 (failed to read result page: error finding value in datum: /Drain at part 0: couldn't find key: struct field with name "Drain")
 09:18:03 ~
$ nomad node status -filter "Drain == TRUE"
Error querying node status: Unexpected response code: 400 (failed to read result page: error finding value in datum: /Drain at part 0: couldn't find key: struct field with name "Drain")
 09:18:08 ~
$ nomad node status -filter "Drain is TRUE"
Error querying node status: Unexpected response code: 400 (failed to create result paginator: failed to read filter expression: 1:10 (9): no match found, expected: "empty", "not" or [ \t\r\n])

Any idea on how to do this?

thank you