Edit of UnixCluster returns 400 error with Version

This request

(
[method] => PUT
[uri] => Array
(
[scheme] => http
[host] => 127.0.0.1
[user] => co_2.rest_user_01
[pass] => XXXXXXXX
[path] => /registry/unix_cluster/unix_clusters/35.json
)

[header] => Array
(
[Content-Type] => application/json
)

[body] => {"RequestType":"UnixClusters","Version":"1.0","UnixClusters":[

{"Version":"1.0","ClusterId":"58","UsernameType":"eppn","UidType":"uid","DefaultShell":"\/bin\/tcsh","HomedirPrefix":"\/home","GidType":"uid","GroupnameType":"eppn","SyncMode":"F"}

]}
)

returns a 400 with error response

{"ResponseType":"ErrorResponse","Version":"1.0","Id":"35","InvalidFields":

{"Version":["Unknown version"]}

}