tdcommon/src/main/java/thredds/server/catalog/CatalogScan.java
public ConfigCatalog getCatalog(File baseDir, String matchRemaining, String filename, CatalogReader reader) throws IOException {
    String relLocation = (matchRemaining.length() >= 1) ? location + "/" + matchRemaining : location;
    File absLocation = new File(baseDir, relLocation);
    ConfigCatalog cc = reader.getFromAbsolutePath(absLocation + "/" + filename);
    if (cc == null)
      logger.warn("Cant find catalog from scan: " + absLocation + "/" + filename);
    return cc;
  }
public ConfigCatalog getCatalog(File baseDir, String matchRemaining, String filename, CatalogReader reader) throws IOException {
    String relLocation = (matchRemaining.length() >= 1) ? location + "/" + matchRemaining : location;
    File absLocation = new File(baseDir, relLocation);
    ConfigCatalog cc = reader.getFromAbsolutePath(absLocation + "/" + filename);
    if (cc == null)
      logger.warn("Cant find catalog from scan: " + absLocation + "/" + filename);
    return cc;
  }
when we have a real catalog  (filename != CATSCAN)