grib/src/main/java/ucar/nc2/grib/collection/GribCollectionMutable.java
File setOrgDirectory(String orgDirectory) {
    this.orgDirectory = orgDirectory;
    directory = new File(orgDirectory);
    if (!directory.exists()) {
      File indexFile = new File(indexFilename);
      File parent = indexFile.getParentFile();
      if (parent.exists())
        directory = parent;
    }
    return directory;
  }
File setOrgDirectory(String orgDirectory) {
    this.orgDirectory = orgDirectory;
    directory = new File(orgDirectory);
    if (!directory.exists()) {
      File indexFile = new File(indexFilename);
      File parent = indexFile.getParentFile();
      if (parent.exists())
        directory = parent;
    }
    return directory;
  }
set from GribCollectionBuilderFromIndex.readFromIndex()