docs: protected Proto searchFromProtoPathOnly(String path, Proto importer) throws Exception
      {
          // proto_path
          File protoFile;
          for (File dir : __protoLoadDirs)
          {
              if ((protoFile = new File(dir, path)).exists())
                  return loadFrom(protoFile, importer);
          }
  
          throw new IllegalStateException("Imported proto " + path +
                  " not found. (" + importer.getSourcePath() + ")");
      }