title: Use buildConfigField defined in build.gradle in another place in build.gradle
body: <p>I have the next chunk of code in my build.gradle:</p>
  
  <pre><code>productFlavors {
          //DIMENSION - APP
          slid {
              dimension "app"
              applicationId "com.slid"
              versionCode 1
              versionName "1.0.0"
  
              manifestPlaceholders = [one_app_id : "273e0-b8f-4c7f-87-0f4eb68da"]
          }
  }
  </code></pre>
  
  <p>What I want to do is access <code>one_app_id</code> from <code>manifestPlaceholders</code> inside my java code. </p>
  
  <p>As I was unable to do so (or at least I was unable to find a way), I want to define a <code>buildConfigField</code> <code>String</code> with the same value <code>273e0-b8f-4c7f-87-0f4eb68da</code> but I'd like to make it a reference to <code>manifestPlaceholders/one_app_id</code> so I don't write the ID two times.</p>
  
  <p>My question is: 
  <code>buildConfigField "String", "ONE__ID", '[reference_here]'</code>
  What do I set instead of <code>[reference_here]</code> ?</p>
  
  <p><strong>OR</strong></p>
  
  <p>How can I do i the other way, i.e. have the ID set as a <code>buildConfigField</code> and then set that reference in the <code>manifestPlaceholder</code>
  For example <code>manifestPlaceholders = [one_app_id: [?!reference_here?!]]</code></p>
  
  <p><strong>P.S.</strong> don't worry, the ID is not valid :)</p>