var time = new GlideDateTime();
gs.info('GMT time is->'+time);
var tz = Packages.java.util.TimeZone.getTimeZone('PST');
time.setTZ(tz);
var timeZoneOffSet = time.getTZOffset();
time.setNumericValue(time.getNumericValue() + timeZoneOffSet);
gs.info('PST time is->'+time);