title: How to add random string to Azure Function Blob Output file name? - The specified block list is invalid
body: <p>I have Blob output working successfully when java function is invoked in non fast cycle.
  But getting error when function are invoked in fast cycle. Since durable singleton are not supported in Java, I just have to make that each file have unique name.</p>
  
  <p>How to add random string or guid to name so that each file get unique name even timestamp is same.</p>
  
  <p>ERROR:</p>
  
  <pre><code>system.Private.CoreLib: Exception while executing function: Functions.TopicTriggerDatalakeOutput. 
  Microsoft.Azure.WebJobs.Host: Error while handling parameter _binder after function returned:. 
  Microsoft.WindowsAzure.Storage: The specified block list is invalid.
  </code></pre>
  
  <p>CODE:</p>
  
  <pre><code>@BlobOutput(
           name = "target", 
          connection = "DataLakeConnString",
          path = "profile/blob_{DateTime}.csv")
          OutputBinding&lt;String&gt; outputItem,
  </code></pre>