code: public <T> HystrixRequestVariable<T> getRequestVariable(final HystrixRequestVariableLifecycle<T> rv) {
          return new HystrixLifecycleForwardingRequestVariable<T>(rv);
      }
docs: Factory method to return an implementation of {@link HystrixRequestVariable} that behaves like a {@link ThreadLocal} except that it
  is scoped to a request instead of a thread.
  <p>
  For example, if a request starts with an HTTP request and ends with the HTTP response, then {@link HystrixRequestVariable} should
  be initialized at the beginning, available on any and all threads spawned during the request and then cleaned up once the HTTP request is completed.
  <p>
  If this method is implemented it is generally necessary to also implemented {@link #wrapCallable(Callable)} in order to copy state
  from parent to child thread.
  
  @param rv
  {@link HystrixRequestVariableLifecycle} with lifecycle implementations from Hystrix
  @return {@code HystrixRequestVariable<T>}