||The main purpose of this component is to setup and clear
ThreadLocal variables that
can otherwise interfere with the smooth running of JIRA by leaking resources or allowing
stale cached information to survive between requests.
||This interface is used as a callback mechanism in the case where "runnable code" has completed
postCall determines that it did not clean
||If you ever need to run code in JIRA off a HTTP request thread then you can sue this class to help setup and clean up
the thread environment.