BuildConfig.DEBUG always return false
<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>