code: private FileNode init(String name) {
          String value;
          File file;
  
          value = System.getProperty(name);
          if (value == null) {
              throw new IllegalStateException("property not found: " + name);
          }
          file = new File(value);
          if (!file.isDirectory()) {
              throw new IllegalStateException(
                  "property " + name + " does not point to a directory: " + value);
          }
          return file(file);
      }
docs: --