A_Tab.getValue method with quite new element instance in callout script

[StabilisOne]

Problem:

I've noticed A_Tab.getValue method in callout can return only Integer from ex. Record_ID of quite new elements / columns implemented by user in new tab,

despite the fact that, for example:

thisHeight = ((BigDecimal)A_Tab.getValue("Height"));

does not return any exception ("Height" is existing element, hardcoded in iD as a standard field in many models)

but 

thisQuiteNewTab_ID=((BigDecimal)A_Tab.getValue("QuiteNewTab_ID"));

returns exception and should be changed to:

thisQuiteNewTab_ID=((Integer)A_Tab.getValue("QuiteNewTab_ID"));

so, cast to BigDecimal could be only a next step in the @script, ex. 

thisQuiteNewTab_IDBigDecimal=BigDecimal.valueOf(thisQuiteNewTab_ID)

Question:

Is it possible and how make A_Tab.getValue method returns directly BigDecimal from quite new element instance ?