Add Owned Field to Bundle
PUT /admin/customfield/ownedFieldBundle/{bundleName}/{fieldName}
Add new owned fields to bundle
PUT /rest/admin/customfield/ownedFieldBundle/{bundleName}/{fieldName}?{description}&{colorIndex}&{login}
Sample
PUT http://localhost:8081/rest/admin/customfield/ownedFieldBundle/New%20bundle%20name/Element%20name?description=element+description&login=root
Cookie: $Version=0; JSESSIONID=8dmapdeyqjdkeab2l6yhf4cu; $Path=/; jetbrains.charisma.main.security.PRINCIPAL=NDgxMzQ5NGQxMzdlMTYzMWJiYTMwMWQ1YWNhYjZlN2JiN2FhNzRjZTExODVkNDU2NTY1ZWY1MWQ3Mzc2NzdiMjpyb290; $Path=/
HTTP/1.1 201 Created
Content-Type: application/xml;charset=UTF-8
Location: https://example.com/youtrack/rest/admin/customfield/ownedFieldBundle/New%20bundle%20name/Element%20name
Content-Length: 0
Server: Jetty(7.2.0.v20101020)
Last modified: 2 February 2017