Transition a linked issue using Groovy expression

[Kimberley Chapman]

Hello

I have zero experience in groovy expressions and I am trying to use JIRA Misc Workflow extensions to transition a linked issue based on a certain condition. I would like to ensure this post function cannot be completed unless a custom field has a certain value in it. 

I have tried:

if(issue.get("customfield_10900") =  2) {
return true;
} else {
return false;
}

and I get the error message - 

startup failed: Script1.groovy: 1: expecting ')', found '=' @ line 1, column 35. if(issue.get("customfield_10900") = 2) { ^ 1 error

It seems that you have tried to perform an illegal workflow operation.

If you think this message is wrong, please contact your JIRA administrators.

If I change it to:

if(issue.get("customfield_10900") >=  2) {
return true;
} else {
return false;
}

I do not get an error message, the linked issue will transition but it ignores the condition (for instance my custom field could say 0 or 1 instead of 2)

Hopefully someone can help. 

Thanks

[Kimberley Chapman]

It may be worth mentioning that the Custom Field is a number field, I am unsure if that makes much difference. 

Thanks