[EventHubs] Warning partition key type (Azure#16909)

* add warning in the docs on partition key accepted type

* address feedback

Author: yunhaoling

sdk/eventhub/azure-eventhub/azure/eventhub/_producer_client.py

@@ -222,6 +222,8 @@ def send_batch(self, event_data_batch, **kwargs):
          A `TypeError` will be raised if partition_key is specified and event_data_batch is an `EventDataBatch` because
          `EventDataBatch` itself has partition_key.
          If both partition_id and partition_key are provided, the partition_id will take precedence.
+         **WARNING: Please DO NOT pass a partition_key of non-string type. The Event Hub service ignores partition_key
+         of non-string type, in which case events will be assigned to all partitions using round-robin.**
         :rtype: None
         :raises: :class:`AuthenticationError<azure.eventhub.exceptions.AuthenticationError>`
          :class:`ConnectError<azure.eventhub.exceptions.ConnectError>`
@@ -281,6 +283,8 @@ def create_batch(self, **kwargs):
         :keyword str partition_key: With the given partition_key, event data will be sent to
          a particular partition of the Event Hub decided by the service.
          If both partition_id and partition_key are provided, the partition_id will take precedence.
+         **WARNING: Please DO NOT pass a partition_key of non-string type. The Event Hub service ignores partition_key
+         of non-string type, in which case events will be assigned to all partitions using round-robin.**
         :keyword int max_size_in_bytes: The maximum size of bytes data that an EventDataBatch object can hold. By
          default, the value is determined by your Event Hubs tier.
         :rtype: ~azure.eventhub.EventDataBatch

sdk/eventhub/azure-eventhub/azure/eventhub/aio/_producer_client_async.py

@@ -253,6 +253,8 @@ async def send_batch(
          A `TypeError` will be raised if partition_key is specified and event_data_batch is an `EventDataBatch` because
          `EventDataBatch` itself has partition_key.
          If both partition_id and partition_key are provided, the partition_id will take precedence.
+         **WARNING: Please DO NOT pass a partition_key of non-string type. The Event Hub service ignores partition_key
+         of non-string type, in which case events will be assigned to all partitions using round-robin.**
         :rtype: None
         :raises: :class:`AuthenticationError<azure.eventhub.exceptions.AuthenticationError>`
          :class:`ConnectError<azure.eventhub.exceptions.ConnectError>`
@@ -316,6 +318,8 @@ async def create_batch(
         :param str partition_key: With the given partition_key, event data will be sent to
          a particular partition of the Event Hub decided by the service.
          If both partition_id and partition_key are provided, the partition_id will take precedence.
+         **WARNING: Please DO NOT pass a partition_key of non-string type. The Event Hub service ignores partition_key
+         of non-string type, in which case events will be assigned to all partitions using round-robin.**
         :param int max_size_in_bytes: The maximum size of bytes data that an EventDataBatch object can hold. By
          default, the value is determined by your Event Hubs tier.
         :rtype: ~azure.eventhub.EventDataBatch