private DecimalFormat getCurrencyFormat() {
        if (options != null && options.getCurrencyFormat() != null) {
            return options.getCurrencyFormat();
        }
        else {
            return (DecimalFormat) DecimalFormat.getCurrencyInstance(locale);
        }
    }
If value is an explicitly set value, then use that value to update the cell, otherwise if
ExcelOptions.isStronglyTypedCells = true then for cells check:
<pre>
Numeric - String that are all numbers make them a numeric cell
Currency - Convert to currency cell so math can be done in Excel
String - fallback to just a normal string cell
</pre>
Possible future enhancement of Date cells as well.

@param column the column from which value comes
@param cell the cell to operate on
@param value the ColumnValue value to put in the cell
primefaces/src/main/java/org/primefaces/util/ExcelStylesManager.java