Behavior for requiring IssueLink when setting resolution to duplicate

[Nathan Parmeter]

Setting up a behavior for requiring  an IssueLink when setting resolution to duplicate.

have this:

import com.atlassian.jira.component.ComponentAccessor
def resolutionField = getFieldByName("resolution")
def linksField = getFieldByName("issuelinks")
def resolution = resolutionField.getValue()

if (((IssueConstant) resolution).getName() == "Duplicate") {
linksField.setRequired(true)
linksField.setHidden(false)
}
else {
linksField.setRequired(false)
linksField.setHidden(false)
}

However im getting the following error:

[common.UserScriptEndpoint]: Script console script failed: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed: Script15.groovy: 5: unable to resolve class IssueConstant @ line 5, column 5. if (((IssueConstant) resolution).getName() == "Duplicate") {

Assistance would be appreciated, I'm sure I am missing something but cant figure it out. 

[Neta Elyakim · Accepted solution]

You are missing the import for IssueConstant, and you need to take the fields as Id and not by name (those are system fields)

Use this:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.IssueConstant

def resolutionField = getFieldById("resolution")
def linksField = getFieldById("issuelinks")
def resolution = resolutionField.getValue()

if (((IssueConstant) resolution).getName() == "Duplicate") {
 linksField.setRequired(true)
 linksField.setHidden(false)
}
else {
 linksField.setRequired(false)
 linksField.setHidden(false)
} 

[Nathan Parmeter]

Thank you, figured it was something simple I was missing.