question: public static Pair < String , String > checkSpecialSearch ( String filter , char [ ] binarySortedPrefixes ) { if ( filter . length ( ) > 1 && Arrays . binarySearch ( binarySortedPrefixes , filter . charAt ( 0 ) ) >= 0 ) { return new Pair < > ( filter . substring ( 0 , 1 ) , filter . substring ( 1 ) ) ; } return null ; }
target:  Check if filter is a special search with prefix Format: [prefix].+ E.g. #tag, ?phrase where # and ? are prefix characters