question: private boolean isNullSetting ( boolean makeDest , MappingType mtd , MappingType mts , StringBuilder result ) { if ( makeDest && ( mtd == ALL_FIELDS || mtd == ONLY_VALUED_FIELDS ) && mts == ONLY_NULL_FIELDS ) { result . append ( "   " + stringOfSetDestination + "(null);" + newLine ) ; return true ; } return false ; }
target:  if it is a null setting returns the null mapping