Setting PartitionKey in Azure Functions

EventHubTrigger.csx

#r "Microsoft.ServiceBus" 

using System;
using System.Text;
using Microsoft.ServiceBus.Messaging;

public static void Run(EventData myEventHubMessage, TraceWriter log)
{
    log.Info($"C# Event Hub trigger function processed a message with partition key: {myEventHubMessage.PartitionKey}");
}

output.txt

2017-10-11T21:00:17  Welcome, you are now connected to log-streaming service.
2017-10-11T21:00:20.041 Function started (Id=1181022f-fb8b-443e-b832-d7352b1f0f5c)
2017-10-11T21:00:20.041 C# Event Hub trigger function processed a message with partition key: abc123
2017-10-11T21:00:20.041 Function completed (Success, Id=1181022f-fb8b-443e-b832-d7352b1f0f5c, Duration=0ms)
2017-10-11T21:00:25.011 Function started (Id=4fbc39a0-ad66-449b-bbf5-b5760ec2685e)
2017-10-11T21:00:25.011 C# Event Hub trigger function processed a message with partition key: abc123
2017-10-11T21:00:25.011 Function completed (Success, Id=4fbc39a0-ad66-449b-bbf5-b5760ec2685e, Duration=0ms)
2017-10-11T21:00:30.030 Function started (Id=7479be7e-ccb5-4060-a936-79bb7c7f8e31)
2017-10-11T21:00:30.030 C# Event Hub trigger function processed a message with partition key: abc123
2017-10-11T21:00:30.030 Function completed (Success, Id=7479be7e-ccb5-4060-a936-79bb7c7f8e31, Duration=0ms)

Timer.csx

#r "Microsoft.ServiceBus" 

using System;
using System.Text;
using Microsoft.ServiceBus.Messaging;

public static void Run(TimerInfo myTimer, TraceWriter log, ICollector<EventData> output)
{
    log.Info($"C# Timer trigger function executed at: {DateTime.Now}");
    var data = new EventData(Encoding.UTF8.GetBytes("Testing"));
    data.PartitionKey = "abc123";
    output.Add(data);
}