question: @ CheckReturnValue @ Deprecated @ Nonnull public static String join ( @ Nonnull String [ ] s , @ Nonnull String delimiter ) { StringBuilder buffer = new StringBuilder ( ) ; for ( int i = 0 ; i < s . length ; i ++ ) { buffer . append ( s [ i ] ) ; if ( i < s . length - 1 ) { buffer . append ( delimiter ) ; } } return buffer . toString ( ) ; }
target:  Join an array of strings, separated by a delimiter