code: @Exported
      public @CheckForNull BuildPtr getOriginal() {
          if (original != null && original.hasPermissionToDiscoverBuild()) {
              return original;
          }
          return null;
      }
docs: The first build in which this file showed up,
  if the file looked like it's created there.
  <p>
  This is considered as the "source" of this file,
  or the owner, in the sense that this project "owns"
  this file.
  
  @return null
  if the file is apparently created outside Hudson or if the current
  user has no permission to discover the job.