CosmosDB Outputbinding does not work for multiple documents

We have a simple function which is triggered by event hub and simply forwards messages to cosmosDB using the cosmosDB output binding.
It works well if we receive and forward one message.
However it does not work when we receive and forward a list of messages using Cardinality.many.
Example:
```
public void run(
@EventHubTrigger(
name = "ConsumeDeviceMessages2",
eventHubName = "@eventhub.name@",
connection = "@iothub.connection@",
consumerGroup = CONSUMER_GROUP,
cardinality = Cardinality.MANY)
List messages,

@CosmosDBOutput(
name = "outputDocument",
databaseName = "@cosmosdb.name@",
collectionName = "@cosmosdb.collection.name@",
connectionStringSetting = "@cosmosdb.connection.appsetting@")
OutputBinding> outputDocument,

final ExecutionContext context) {
outputDocument.setValue(messages);
}
```
If this is triggered an error occurs:

`[Error] Executed 'Functions.SaveIotDeviceMessages' (Failed, Id=a845d74b-861a-40e7-a6f2-f5b7032b2cf2)Value cannot be null.Parameter name: document`

Configuration seems pretty basic and works on another function where we forward multiple messages to a queue instead.

Any idea why it is not working for cosmosDB? The documentation states its working for .NET and Javascript, no information about Java though.

Thanks and regards.

Inizia riproducendo la funzione Java con EventHubTrigger Cardinality.MANY e CosmosDB usando OutputBinding>. Traccia il modo in cui l'output binding CosmosDB per Java gestisce outputDocument.setValue(messages) e confronta il suo comportamento con il supporto documentato di .NET e JavaScript. Il lavoro è completato quando viene identificato se in Java sono supportati più documenti e il comportamento risultante viene registrato o corretto.

Scritto dal modello di indicizzazione a partire dal testo della issue.