/*
* This example script  console script updates the  checkbox  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." 
*/

// Get the issue key
def issueKey = '<IssueKeyHere>'
def checkboxField = "<CheckBoxFieldIDHere>"

// Update the issue and add checkbox values to it.
def result = put("/rest/api/2/issue/${issueKey}")
        .header('Content-Type', 'application/json')
        .body([
        fields: [
               (checkboxField): [ // Initialise the  array
                               [ //value of each checkbox value
                                 value: "<CheckboxValueHere>",
                               ],
                               [
                                 value: "<CheckboxValueHere>",
                               ]
                ]
        ]
])
        .asString()