We have created a user defined function for retrieving data to populate the cell. We tried wiring through XEL and TLD but those were untestable because the Zats framework doesn't always notice the function.
We have it wired the way POI recommends it and we can test successfully that way. The function works properly and is tested.
However we are receiving a NullPointerException in FormulaParser at line 175 because XSSFName is returning a null from getRefersToFormula(...).