Convert JUEL execution.getVariable("varName") as null safe variable access

[ingorichtsmeier]

What should we do?

Take a closer look at JUEL expressions with content ${execution.getVariable("varName")}.

Customers used it to access variables, that may not exist as process variable. They use them to avoid a PropertyNotFoundException during expression evaluation.

Find a FEEL expression, that does the same.

Why should we do it?

I've seen this expression in some of the recent Migration talks and workshops.

It will simplify the diagram conversion.