title: Bigtable authentication in java
body: <p>I am looking for an alternative way to authenticate in Bigable.
  Default approach involves the environment variable, which concerns me.</p>
  
  <p>I found <a href="https://developers.google.com/identity/protocols/application-default-credentials" rel="nofollow"><code>GoogleCredential</code></a> class. It can read json key file with fromStream, but how to use the new instance of <code>GoogleCredential</code>.
  There is no method to <code>setApplicationDefault()</code>. I need override it somehow.</p>
  
  <p>HBase code doesn't know anything about <code>GoogleCredential</code>.</p>