BPMN4S DSL does not support `get()` on multi-dimensional lists

[damascenodiego]

Summary

The BPMN4S DSL does not allow the get() function to be used on multi-dimensional lists (as in List<List<T>>).
As a result, nested list elements cannot be accessed in expressions or data mappings.

Reproducer: test.bpmn.txt

Steps to Reproduce

Given the following type definition:

listOfListOfStrings : List<List<String>>

and the initialization

 listOfListOfStrings = <string[][]>[
     <string[]>['0a','0b','0c'],
     <string[]>['1a','1b','1c'],
     <string[]>['2a','2b','2c']
 ]

attempt to evaluate any of the expressions below:

get(config.listOfListOfStrings, 0) // expected returned value: ['0a', '0b', '0c']
get(get(config.listOfListOfStrings, 0), 0) // expected returned value: '0a'

Actual Behavior

The DSL rejects the expressions to access items in multi-dimensional lists (List<List>).

Impact

Users cannot access elements of nested lists, limiting the use of hierarchical data structures in BPMN4S models.