code: public void setOnNonEmptyWorkDirectory(String value) {
      try {
        this.nonEmptyWorkDirAction = NonEmptyWorkDirectoryAction.valueOf(value.toUpperCase(Locale.ROOT));
      } catch (IllegalArgumentException e) {
        throw new IllegalArgumentException("OnNonEmptyWorkDirectory accepts any of: "
            + Arrays.toString(NonEmptyWorkDirectoryAction.values()) + ", value is not valid: " + value);
      }
    }
docs: Determines the behavior on detecting non-empty existing current working
  directory for a forked JVM, before the tests commence. This action is performed
  only if work directory isolation is set to true (see {@link #setIsolateWorkingDirectories(boolean)}).