public IDeviceID getDeviceID() {
    return deviceID;
  }
The {@link DeviceEntry} shall have {@code null} suffix in its {@link IDeviceID}, e.g. "a.b.null".
However, in other places related to {@link TableDeviceSchemaCache} or {@link ISchemaRegion}, the
{@code null}s are trimmed thus will not appear in the {@link IDeviceID}, and it will be like
"a.b".
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/metadata/DeviceEntry.java