+* This example script  console script updates a multi select list field on an issue.

+* "All right, title and interest in this code snippet shall remain the exclusive intellectual property of Adaptavist Group Ltd and its affiliates. Customers with a valid ScriptRunner

+* license shall be granted a  non-exclusive, non-transferable, freely revocable right to use this code snippet only within their own instance of Atlassian products. This licensing notice cannot be removed or

+* amended and must be included in any circumstances where the code snippet is shared by You or a third party." 

+*/

+

+// Specify the issue key of the issue to update below

+def issue = "<IssueKeyHere>"

+

+// Specify the ID of the custcom field below e.g customfield_10012

+def MultiSelectField = "<MultiSelectListCustomFieldIdHere>".toString()

+

+

+// The rest call to update the multi user picker field. 

+// Note: This script must be run as the ScriptRunner add on user

+def setMultiSelectField = put("/rest/api/2/issue/"+ issue)

+        .header('Content-Type', 'application/json')

+        .queryString("overrideScreenSecurity", Boolean.TRUE)

+        .body([

+            // Specify the update structure to update the Multi Select list field and its Array List Data Structure that it uses

+            update:

+                [

+                    (MultiSelectField): [

+                        // Specify the add commands to add each option into the multi select list field as a comma seperated list of the option values to be set.

+                        // Note these option values must be valid option values that can be selected on the edit issue form inside of Jira. 

+                        [add: [value: "<OptionValueHere>"]],

+                        [add: [value: "<OptionValueHere>"]]

+                        ]

+                

+                ]

+        ])

+        .asString()

+        .body

+