Bulk Update Multiple Issue Resolutions

// The Name of the resolution to be set
def resolutionName = 'Cannot Reproduce'

// Get all issues matching the specified JQL Query
Issues.search("project = TEST AND issueType = Bug").each { issue ->
    issue.transition('Done') {
        setResolution(resolutionName)
    }
    logger.info("Resolution set to ${resolutionName} for the ${issue.key} issue")
}