Substring and contains in painless

Sorry Alex it is a painless script which was found in documentation

  1. https://www.elastic.co/blog/using-painless-kibana-scripted-fields

what i was trying to accomplish was get all strings which was word v3 in parsed field which has value like
.... /appname/api/v3/bdq/rules/
.../appname/api/v3/internal/rules/