Prior to JSD 3.1, the Customer request Type fields value could be retrieved using REST when the field was visible on screen. It followed a format of xx/yy-yy} with {{xx being the lower cased project key involved, and the yy-yy value being the name of the Request Type, lower cased, with spaces replacing hyphens. This allowed API initialization of issues with valid Customer Request Types.

In JSD 3.1, it appears that the REST response for the Customer Request Type has drastically changed, relating no doubt to the new JSD REST API. However, in doing this, the 'new' format seems to have removed the only sane place to locate the value required to initialize the custom field:

customfield_10000: {
_links: {
self: "http://localhost:8080/rest/servicedeskapi/request/10501",
jiraRest: "http://localhost:8080/rest/api/2/issue/10501"
},
requestType: {
id: 15,
_links: {
self: "http://localhost:8080/rest/servicedeskapi/servicedesk/2/requesttype/15"
},
name: "Report a system problem",
description: "Having trouble with a system?",
helpText: "",
serviceDeskId: 2
},
currentStatus: {
status: "Waiting for support",
statusDate: {
iso8601: "2016-02-24T14:38:52+0000",
friendly: "Yesterday 2:38 PM",
epochMillis: 1456324732459
}
}
},

With command line wrangling:

curl -u admin:admin -H "X-ExperimentalApi: opt-in" http://localhost:8080/rest/servicedeskapi/servicedesk/2/requesttype/15

... to opt into the experimental API, the drill down into requesttype offers little more:

{"id":15,
"_links":{"self":"http://localhost:8080/rest/servicedeskapi/servicedesk/2/requesttype/15"},
"name":"Report a system problem",
"description":"Having trouble with a system?",
"helpText":"",
"serviceDeskId":2}

The only place that the Value data required to initialize the Customer Request Type is now in the database, making it much more complex for users to locate.

Surely, it is an oversight to not include the value of the Customer Request Type in its REST response, marking as a bug on that basis - I would have tagged 1.3.1, but 1.2.7 is the latest version available).