Unapprovable RejectedAccessException when using Tuple in Jenkinsfile - jenkins

Question

I tried to use Tuple in a Jenkinsfile.
The line I wrote is def tupleTest = new Tuple('test', 'test2').
However, Jenkins did not accept this line and keep writing the following error to the console output:
No such constructor found: new groovy.lang.Tuple java.lang.String java.lang.String. Administrators can decide whether to approve or reject this signature.
...
org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: No such constructor found: new groovy.lang.Tuple java.lang.Integer java.lang.String
...
When I visited the "Script Approval" configuration I could not see any scripts that pend approval.
Following this link, I tried to install and enable the "Permissive Security" plugin, but it did not help either - The error was the same.
I even tried to manually add the problematic signature to the scriptApproval.xml file. After I added it, I was able to see it in the list of approved signatures, but the error still remained.
Is there something I am doing wrong?

Answer 1

I had the same issue trying to use tuple on jenkins so I found out that I can simply use a list literal instead:
def tuple = ["test1", "test2"]
which is equivalent to
def (a, b) = ["test1", "test2"]
So now, instead of returning a tuple, I am returning a list in my method
def myMethod(...) {
...
return ["test 1", "test 2"]
}
...
def (a, b) = myMethod(...)

Answer 2

This is more or less a problem caused by groovy.lang.Tuple constructor + Jenkins sandbox Groovy mode. If you take a look at the constructor of this class you will see something like this:
package groovy.lang;
import java.util.AbstractList;
import java.util.List;
public class Tuple extends AbstractList {
private final Object[] contents;
private int hashCode;
public Tuple(Object[] contents) {
if (contents == null) throw new NullPointerException();
this.contents = contents;
}
//....
}
Groovy sandbox mode (enabled by default for all Jenkins pipelines) ensures that every invocation passes script approval check. It's not foolproof, and when it sees new Tuple('a','b') it thinks that the user is looking for a constructor that matches exactly two parameters of type String. And because such constructor does not exists, it throws this exception. However, there are two simple workarounds to this problem.
Use groovy.lang.Tuple2 instead
If your tuple is a pair, then use groovy.lang.Tuple2 instead. The good news about this class is that it provides a constructor that supports two generic types, so it will work in your case.
Use exact Object[] constructor
Alternatively, you can use the exact constructor, e.g
def tuple = new Tuple(["test","test2"] as Object[])
Both options require script approval before you can use them (however, in this case both constructors appear in the in-process script approval page).