static String getValue ( final Map < String , Features > featureTable , final String extension ) { final List < String > buf = new ArrayList <> ( ) ; for ( final Features f : featureTable . values ( ) ) { final List < String > v = f . getFeature ( extension ) ; if ( v != null ) { buf . addAll ( v ) ; } } if ( buf . isEmpty ( ) ) { return null ; } else { return StringUtils . join ( buf , "," ) ; } }
Get all and combine extension values