question: static void checkMethodDesc ( final String desc ) { if ( desc == null || desc . length ( ) == 0 ) { throw new IllegalArgumentException ( "Invalid method descriptor (must not be null or empty)" ) ; } if ( desc . charAt ( 0 ) != '(' || desc . length ( ) < 3 ) { throw new IllegalArgumentException ( "Invalid descriptor: " + desc ) ; } int start = 1 ; if ( desc . charAt ( start ) != ')' ) { do { if ( desc . charAt ( start ) == 'V' ) { throw new IllegalArgumentException ( "Invalid descriptor: " + desc ) ; } start = checkDesc ( desc , start , false ) ; } while ( start < desc . length ( ) && desc . charAt ( start ) != ')' ) ; } start = checkDesc ( desc , start + 1 , true ) ; if ( start != desc . length ( ) ) { throw new IllegalArgumentException ( "Invalid descriptor: " + desc ) ; } }
target:  Checks that the given string is a valid method descriptor.