@Override
            public void completed() {
                if (state.retrying) {
                    scope.execCount.incrementAndGet();
                    if (entityProducer != null) {
                       entityProducer.releaseResources();
                    }
                    scope.scheduler.scheduleExecution(
                            request,
                            entityProducer,
                            scope,
                            (r, e, s, c) -> execute(r, e, s, chain, c),
                            asyncExecCallback,
                            state.delay);
                } else {
                    asyncExecCallback.completed();
                }
            }
Request executor in the asynchronous request execution chain that is
responsible for making a decision whether a request that failed due to
an I/O exception or received a specific response from the target server should
be re-executed.
<p>
Further responsibilities such as communication with the opposite
endpoint is delegated to the next executor in the request execution
chain.
</p>
<p>
If this handler is active, pay particular attention to the placement
of other handlers within the handler chain relative to the retry handler.
Use {@link ChainElement#RETRY} as name when referring to this handler.
</p>
<p>
If a custom handler is placed <b>before</b> the retry handler, the handler will
see the initial request and the final outcome after the last retry. Elapsed time
will account for any delays imposed by the retry handler.
</p>

<p>
A custom handler which is placed <b>after</b> the retry handler will be invoked for
each individual retry. Elapsed time will measure each individual http request,
without the delay imposed by the retry handler.
</p>

@since 5.0
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/AsyncHttpRequestRetryExec.java