@CosmosDBInput ignores partitionKey

[eriktim]

In my Micronaut Azure Function I am using a binding @CosmosDBInput for event-sourcing like this:

public class ChatRoomFunction extends AzureFunction {

  @FunctionName("handleCommand")
  public HttpResponseMessage handleCommand(
    @HttpTrigger(
      name = "req",
      methods = HttpMethod.POST,
      authLevel = AuthorizationLevel.ANONYMOUS)
    final HttpRequestMessage<Command> request,
    @CosmosDBInput(
      name = "events",
      connectionStringSetting = CONNECTION_STRING,
      databaseName = DATABASE_NAME,
      collectionName = "events",
      partitionKey = "events--{id}") final List<Event> events,
    final ExecutionContext context
  ) {
     // function body intentionally left out
  }
}

// with

public class Command {
  private UUID id;

  // more fields, getters, setters
}

// and

public class Event {
  private String streamId; // this is the CosmosDB partition key

  // more fields, getters, setters
}

Before, I tried doing this using @TableInput which seemed to worked fine. Now I've switched to CosmosDB and for some reason it seems to ignore my @CosmosDBInput's partitionKey value.

Expected: events should contain a list of only Events having a certain streamId as matched by the binding parameter of the request body, i.e. id.

Actual: events contains a list of ALL Events present in the events collection.

Am I missing something here? This is what the partitionKey is for, right?