[ONOS-YANG-DEMO1]Device is getting disconnected and followed by time-out exception for get interface request(queried for updating port statistics)

Problem "device is not able to handle the request and returning -1" is resolved with code changes suggested by Andrea.

java.lang.IllegalArgumentException: org.onosproject.netconf.NetconfException: Failed to retrieve Interfaces
at org.onosproject.drivers.huawei.HuaweiDeviceDescription.getInterfaces(HuaweiDeviceDescription.java:190)
at org.onosproject.drivers.huawei.HuaweiDeviceDescription.discoverPortStatistics(HuaweiDeviceDescription.java:180)
at org.onosproject.provider.netconf.device.impl.NetconfDeviceProvider.updatePortStatistics(NetconfDeviceProvider.java:400)[199:org.onosproject.onos-providers-netconf-device:1.10.0.SNAPSHOT]
at org.onosproject.provider.netconf.device.impl.NetconfDeviceProvider.checkAndUpdateDevice(NetconfDeviceProvider.java:391)[199:org.onosproject.onos-providers-netconf-device:1.10.0.SNAPSHOT]
at org.onosproject.provider.netconf.device.impl.NetconfDeviceProvider.lambda$checkAndUpdateDevices$4(NetconfDeviceProvider.java:442)[199:org.onosproject.onos-providers-netconf-device:1.10.0.SNAPSHOT]
at java.lang.Iterable.forEach(Iterable.java:75)[:1.8.0_111]
at org.onosproject.provider.netconf.device.impl.NetconfDeviceProvider.checkAndUpdateDevices(NetconfDeviceProvider.java:423)[199:org.onosproject.onos-providers-netconf-device:1.10.0.SNAPSHOT]
at org.onosproject.provider.netconf.device.impl.NetconfDeviceProvider$2.run(NetconfDeviceProvider.java:202)[199:org.onosproject.onos-providers-netconf-device:1.10.0.SNAPSHOT]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)[:1.8.0_111]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)[:1.8.0_111]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)[:1.8.0_111]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)[:1.8.0_111]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_111]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_111]
at java.lang.Thread.run(Thread.java:745)[:1.8.0_111]
Caused by: org.onosproject.netconf.NetconfException: Failed to retrieve Interfaces
... 15 more
Caused by: java.util.concurrent.TimeoutException
at java.util.concurrent.CompletableFuture.timedGet(CompletableFuture.java:1771)[:1.8.0_111]
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1915)[:1.8.0_111]
at org.onosproject.netconf.ctl.NetconfSessionImpl.sendRequest(NetconfSessionImpl.java:308)
at org.onosproject.netconf.ctl.NetconfSessionImpl.requestSync(NetconfSessionImpl.java:283)
at org.onosproject.netconf.ctl.NetconfSessionImpl.get(NetconfSessionImpl.java:361)
at org.onosproject.drivers.huawei.HuaweiDeviceDescription.getInterfaces(HuaweiDeviceDescription.java:187)
... 14 more