question: default < T > void forEachMatchingFieldName ( String regex , int groupNumber , BiFunction < String , String , T > groupExtractor , BiConsumer < String , T > function ) { forEachMatchingFieldName ( Pattern . compile ( regex ) , groupNumber , groupExtractor , function ) ; }
target:  For all fields whose names match the given regular expression, extract a value from the specified group in the regular expression and call the supplied function.