question: public Map < String , String > merge ( Map < String , String > curProps , Map < String , String > newProps ) throws IOException { Map < String , String > props = new HashMap < > ( newProps ) ; for ( Map . Entry < String , String > e : curProps . entrySet ( ) ) { String name = e . getKey ( ) ; String curValue = e . getValue ( ) ; if ( props . containsKey ( name ) ) { props . put ( name , curValue ) ; } } return props ; }
target:  Merges two bunches of the properties from current and new configurations.