Global variables are not reachable in functions

[tapraj]

I have written a scriptrunner Behaviour in which the behaviour used multiple fields using getfieldByName() function.

The variables are then later used in functions according requirement.

The blocker is to avoid performance issue I have, I cant define the customfield variables again and again so I tried making the variables storing customfield as a global variable.

using following approaches 

https://issues.apache.org/jira/browse/GROOVY-546
https://code-maven.com/groovy-variable-scope

But the variables cant be made global using any of the above.

Any Suggestions?

[PD Sheehan]

Can you share some of your concrete examples? 

Here is a console example, that works just like these links describe:

I can't imagine why behaviours would work differently.