return Platform.nullToEmpty(string);
  }

  /**
   * Returns the given string if it is nonempty; {@code null} otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} itself if it is nonempty; {@code null} if it is empty or null
   */
  public static @Nullable String emptyToNull(@Nullable String string) {
    return Platform.emptyToNull(string);

	// Setup test environment.
	if err = xlStorage.MakeVol(t.Context(), "success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	// TestXLStorage failure cases.
	vol := slashpath.Join(path, "nonempty-vol")
	if err = os.Mkdir(vol, 0o777); err != nil {
		t.Fatalf("Unable to create directory, %s", err)
	}
	if err = os.WriteFile(slashpath.Join(vol, "test-file"), []byte{}, os.ModePerm); err != nil {

        assertEquals("{constraints.Length.message}", FessMessages.CONSTRAINTS_Length_MESSAGE);
        assertEquals("{constraints.NotBlank.message}", FessMessages.CONSTRAINTS_NotBlank_MESSAGE);
        assertEquals("{constraints.NotEmpty.message}", FessMessages.CONSTRAINTS_NotEmpty_MESSAGE);
        assertEquals("{constraints.Range.message}", FessMessages.CONSTRAINTS_Range_MESSAGE);