title: Populate picklist dynamically based on filepath type in Azure Devops?
body: <p>In Azure Devops, I am building one extension with build task where input picklist field is dependent on the another input filepath field. 
  When the user provides an input filepath, I wanted to dynamically read and populate the picklist with new items.
  I tried to search and implement but couldn't find a way. 
  Any help or guidance will be appreciated. I found the below example to help me out for static values.</p>
  
  <pre><code>{
     "name": "action",
     "type": "pickList",
     "label": "Action",
     "defaultValue": "Publish",
     "required": true,
     "helpMarkDown": "Select the Action to perform",
     "options": {
       "Publish": "Publish Changes",
       "Script": "Script Changes",
       "DeployReport": "Generate Deployment Report"
     }
   }
  </code></pre>