protected MtuRequest requestMtu(@IntRange(from = 23, to = 517) final int mtu) {
		return Request.newMtuRequest(mtu).setRequestHandler(requestHandler);
	}
Requests new MTU. On Android Lollipop or newer it will send the MTU request to the connected
device. On older versions of Android the
{@link MtuCallback#onMtuChanged(BluetoothDevice, int)} set with
{@link MtuRequest#with(MtuCallback)} will be called with current MTU value.
<p>
The returned request must be either enqueued using {@link Request#enqueue()} for
asynchronous use, or awaited using await() in synchronous execution.
<p>
Starting from version 2.7.3 the maximum packet size is 512 bytes, even if the MTU is set to
517. See: <a href="https://github.com/NordicSemiconductor/Android-BLE-Library/issues/541">#541</a>.

@return The request.
ble/src/main/java/no/nordicsemi/android/ble/BleManager.java