title: BuildConfig.DEBUG always return false
body: <p>Why does <code>BuildConfig.DEBUG</code> return false, when I run the application?</p>
  
  <p>I use it to control the log like the following:</p>
  
  <pre><code>public static void d(String LOG_TAG, String msg){
      if(BuildConfig.DEBUG){
          Log.d(LOG_TAG,msg);
      }
  }
  </code></pre>