I want to know the current time of the machine from which a request is made to my api written in java. Is it possible to do that using some function of HttpServletRequest?
No! Not using the java api request as requests are created by users .But if you have a UI application sending requests to java application that application can get the client machine's date & your Ui code can send this date in request.
var currentDate = new Date();
you can format and send the date now to server.