Cannot write data to a specific partition

[zzgzy]

Feature Requests:

• What issue are you trying to solve?
  cannot write data to a specific partition
• How do you want to solve it?
  want to understand if it's a bug or the I use it in a wrong way
• What is your use case for this feature?
  want to send some signal data to event hub and have to send to every partition.

Bug Report:

• Actual behavior
  I specified the "partitionId" column (with “body”) in the data query and send the data to 3 different partitions. When processing the data from a c# app, I noticed that the signal messages are not present in every partitions.

    messages
      .select("partitionId", "body")
      .write
      .format("eventhubs")
      .option("checkpointLocation", XXX)
      .options(ehConf.toMap).save()   // messages: Dataset[(String, String)]

• Expected behavior
  The messages should be sent to every single partitions defined by the partitionId column.
• Spark version
  2.4 on HDInsight
• spark-eventhubs artifactId and version
  azure-eventhubs-spark_2.11:2.3.15

[nyaghma]

The change is included in version 2.3.18.