cdm/src/main/java/ucar/nc2/util/DiskCache2.java
static public DiskCache2 getDefault() {
    String root = System.getProperty("nj22.cache");

    if (root == null) {
      String home = System.getProperty("user.home");

      if (home == null)
        home = System.getProperty("user.dir");

      if (home == null)
        home = ".";

      root = home + "/.unidata/cache/";
    }

    DiskCache2 result = new DiskCache2();
    result.setRootDirectory(root);
    result.alwaysUseCache = false;
    return result;
  }
static public DiskCache2 getDefault() {
    String root = System.getProperty("nj22.cache");

    if (root == null) {
      String home = System.getProperty("user.home");

      if (home == null)
        home = System.getProperty("user.dir");

      if (home == null)
        home = ".";

      root = home + "/.unidata/cache/";
    }

    DiskCache2 result = new DiskCache2();
    result.setRootDirectory(root);
    result.alwaysUseCache = false;
    return result;
  }
Default DiskCache2 strategy: use $user_home/.unidata/cache/, no scouring, alwaysUseCache = false
Mimics default DiskCache static class