Are there ways to make @Field private in scope of single script in jenkins?

Here in the @Field annotation documentation written that:
The annotated variable will become a private field of the script class.
But this is not working in Jenkins:

If i have two scripts, one of them loaded another one, @Field annotated variable becomes global:

/* test.groovy */

import groovy.transform.Field

@Field def scriptPrivateVar

def main() {
  node('main') {
    checkout scm
    scriptPrivateVar = 'a'
    def module = load("${pwd()}/module.groovy")



/* module.groovy */
def callPrivate() {
  echo "private var: ${this.scriptPrivateVar}"

return this  

And the output is:

20:59:32  private var: a

Am i understand correctly that the only way to make scriptPrivateVar global in scope of on only test.groovy script → define it as global without @Field? Any options?