git clone https://github.com/openjdk-mirror/jdk.git cd jdk git checkout jdk8u/jdk8u/master
And go ahead find the class. Most classes can be found under /src/share/classes/,
“Rest is architectural style for distributed hypermedia systems”: REpresentational State Transfer (Rest != http)
Data and functionality are resources.
Resources are accessible using URI.
The resources are acted upon by using simple operations. HTTP is an implementation of a standardised interface.
Resources can have Metadata to express representation format, control caching, auth and access_control, etc.