Hi,
I'm trying to PoC some functionality in a JIRA 6.4 instance where we use Script Runner clone an issue to a user selected project and link to the original issue. I have done this before but in a later version.
For clarity this question is solely in relation to 6.4.11 and "upgrade" isn't a useful answer.
I've done my research and found similar issues (including on the Community answer I lifted the code from) but no solutions thus far. As far as I can work out SR can't get the method from Mutable Issue but it certainly should be there according to the docs.
I'm not really any kind of programmer/scripter/coder whatever so I'm quite happy for someone to point out that I've done something very basic wrong.
Here's the code:
import com.atlassian.jira.issue.MutableIssue;
def cfObj = customFieldManager.getCustomFieldObject('customfield_10102')
def cfValue = issue.getCustomFieldValue(cfObj)
if (cfValue != null){
issue.setProjectId(cfValue.id)
}
Here's the error:

"Cannot find matching method com.atlassian.jira.issue.MutableIssue#setProjectID"
Any ideas