question: public static String append ( final CharSequence url , final Object ... params ) { final String baseUrl = url . toString ( ) ; if ( params == null || params . length == 0 ) return baseUrl ; if ( params . length % 2 != 0 ) throw new IllegalArgumentException ( "Must specify an even number of parameter names/values" ) ; final StringBuilder result = new StringBuilder ( baseUrl ) ; addPathSeparator ( baseUrl , result ) ; addParamPrefix ( baseUrl , result ) ; addParam ( params [ 0 ] , params [ 1 ] , result ) ; for ( int i = 2 ; i < params . length ; i += 2 ) { result . append ( '&' ) ; addParam ( params [ i ] , params [ i + 1 ] , result ) ; } return result . toString ( ) ; }
target:  Append given name/value pairs as query parameters to the base URL <p> The params argument is interpreted as a sequence of name/value pairs so the given number of params must be divisible by 2.