question: public static PropertyFilter valueOf ( String filterString ) { if ( filterString == null || filterString . length ( ) == 0 || ALL . equals ( filterString = filterString . trim ( ) ) ) { return ALL_FILTER ; } else if ( filterString . equalsIgnoreCase ( NONE ) ) { return NONE_FILTER ; } return new PropertyFilter ( filterString ) ; }
target:  Construct new Property Filter.