protected SleepRequest sleep(@IntRange(from = 0) final long delay) {
		return Request.newSleepRequest(delay).setRequestHandler(requestHandler);
	}
Enqueues a sleep operation with given duration. The next request will be performed after
at least given number of milliseconds.
<p>
The returned request must be either enqueued using {@link Request#enqueue()} for
asynchronous use, or awaited using await() in synchronous execution.

@param delay the delay in milliseconds.
@return The request.
ble/src/main/java/no/nordicsemi/android/ble/BleManager.java