question: public Builder measurementMappings ( Map < String , String > measurementMappings ) { Map < String , Pattern > mappingsByPattern = new HashMap < String , Pattern > ( ) ; for ( Map . Entry < String , String > entry : measurementMappings . entrySet ( ) ) { try { final Pattern pattern = Pattern . compile ( entry . getValue ( ) ) ; mappingsByPattern . put ( entry . getKey ( ) , pattern ) ; } catch ( PatternSyntaxException e ) { throw new RuntimeException ( "Could not compile regex: " + entry . getValue ( ) , e ) ; } } this . measurementMappings = mappingsByPattern ; return this ; }
target:  Map measurement to a defined measurement name, where the key is the measurement name and the value is the reqex the measurement should be mapped by.