code: public String getMainDexClassesRulesPath()
      {
          File mainDexClassesRules = new File( getBuildToolInfo().getLocation(),
                  "mainDexClasses.rules" );
          if ( mainDexClassesRules.exists() ) 
          {
              return mainDexClassesRules.getAbsolutePath();
          }
          throw new InvalidSdkException( "Cannot find " + mainDexClassesRules );
      }
docs: Get the path for mainDexClasses.rules
  @return