"id": "P1", "description": "starting with # and then digits and then one or more spaces", "regex": "^\\#\\s(\\d+)\\s", "inputField": "preProcessedMerchantName", "outputField": "cleanMerchantName", "trimOutput": "true",...

Still tuning it...

https://stackoverflow.com/questions/27745/getting-parts-of-a-url-regex