NumberConverter allow values like 'HelloWorld123' to be converter into 123 as BigDecimal. This can lead into wrong data, without user noticing.
There are some non digit characters like dot ('.') and comma (',') that we should allow, in order to ease reading of big numbers like:
1.000.000,12 or 1,000,000.12 depending on the Locale.
https://github.com/rjimgal/jbehave-bigdecimal-converter project demonstrates how '0x1A' is converted into BigDecimal 1, while one could expect NumberConverter to support hex inputs.