code: private static boolean isInternal(String clsName) {
          boolean internal = false;
          for (String internalPackage : internalPackages) {
              if (clsName.startsWith(internalPackage)) {
                  internal = true;
                  break;
              }
          }
  
          if (internal) {
              for (String externalPackage : externalPackages) {
                  if (clsName.startsWith(externalPackage)) {
                      internal = false;
                      break;
                  }
              }
          }
  
          return internal;
      }
docs: determines if the class in question is an internal class by looking at package prefixes
  
  @param clsName
  the name of the class to check
  @return whether the class is internal