title: "The parameter LinuxFxVersion has an invalid value" when creating WebApp resource from Node.js
body: <p>I am trying to create a simple WebApp using the Azure SDK for JS in a Node.js environment, but I keep getting the response:</p>
  
  <pre><code>{
    "Code":"BadRequest",
    "Message":"The parameter LinuxFxVersion has an invalid value.",
    "Target":null,
    "Details":[
      {"Message":"The parameter LinuxFxVersion has an invalid value."},
      {"Code":"BadRequest"},
      {"ErrorEntity": {
          "ExtendedCode":"01007",
          "MessageTemplate":"The parameter {0} has an invalid value.",
          "Parameters":["LinuxFxVersion"],
          "Code":"BadRequest",
          "Message":"The parameter LinuxFxVersion has an invalid value."}
      }],
    "Innererror":null
  }
  </code></pre>
  
  <p>I've tried a variety of different sets of properties and environments with no success. I always get this error. Here's a snippet of the TypeScript code I am using:</p>
  
  <pre><code>    const wsmClient: WebSiteManagementClient...
      const webAppName: string...
      const servicePlanId: string...
      const rgName: string...
      const envelope: Site = {
        name: webAppName,
        location: 'westus2',
        kind: 'app,linux',
        serverFarmId: servicePlanId,
        siteConfig: {
          linuxFxVersion: 'JAVA|11-java11'
        }
      };
      const appResp = await wsmClient.webApps.createOrUpdate(
        rgName,
        webAppName,
        envelope
      );
  </code></pre>
  
  <p>What am I doing wrong?</p>