question: public final MessageBuilder header ( String name , String value ) { JsoArray < Pair > headers = message . getHeaders ( ) ; if ( headers == null ) { headers = JsoArray . create ( ) ; } for ( int i = 0 ; i < headers . size ( ) ; i ++ ) { Pair header = headers . get ( i ) ; if ( name . equals ( header . getName ( ) ) ) { header . setValue ( value ) ; return this ; } } Pair header = Pair . create ( ) ; header . setName ( name ) ; header . setValue ( value ) ; headers . add ( header ) ; message . setHeaders ( headers ) ; return this ; }
target:  Sets a request header with the given name and value. If a header with the specified name has already been set then the new value overwrites the current value.