import static com.amazonaws.util.SdkRuntime.shouldAbort;
Returns the underlying input stream, if any, from the subclass; or null
if there is no underlying input stream.
Aborts with subclass specific abortion logic executed if needed.
Note the interrupted status of the thread is cleared by this method.
Can be used to provide abortion logic prior to throwing the
AbortedException. No-op by default.
WARNING: Subclass that overrides this method must NOT call
super.release() or else it would lead to infinite loop.