I'm reading data from the default endpoint of an IoT hub in azure using the kafka connector in Databricks.  Most data items are straight forward, but the device id and the timestamp I haven't been able to properly decode

For example, the key-value map of the headers  {"key": "iothub-enqueuedtime", "value": "gwAAAZAMsGjg"}  should be a recent timestamp.  Any ideas on how to decode this, using pyspark?