throw new UnsupportedOperationException();
    }

    @Override
    public boolean retainAll(Collection<?> elementsToRetain) {
      throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
      throw new UnsupportedOperationException();
    }

    @Override
    public int setCount(@ParametricNullness E element, int count) {

    public boolean add(@ParametricNullness E element) {
      throw new UnsupportedOperationException();
    }

    @Override
    public int add(@ParametricNullness E element, int occurrences) {
      throw new UnsupportedOperationException();
    }

    @Override
    public boolean addAll(Collection<? extends E> elementsToAdd) {
      throw new UnsupportedOperationException();
    }

    @Override

   * are inclusive). For example, to match any lowercase letter of the English alphabet, use {@code
   * CharMatcher.inRange('a', 'z')}.
   *
   * @throws IllegalArgumentException if {@code endInclusive < startInclusive}
   */
  public static CharMatcher inRange(char startInclusive, char endInclusive) {
    return new InRange(startInclusive, endInclusive);
  }

  /**

   * are inclusive). For example, to match any lowercase letter of the English alphabet, use {@code
   * CharMatcher.inRange('a', 'z')}.
   *
   * @throws IllegalArgumentException if {@code endInclusive < startInclusive}
   */
  public static CharMatcher inRange(char startInclusive, char endInclusive) {
    return new InRange(startInclusive, endInclusive);
  }

  /**

   *       into account
   *   <li>the appropriate truncation indicator may be locale-dependent
   *   <li>it is safe to use non-ASCII characters in the truncation indicator
   * </ul>
   *
   * @throws IllegalArgumentException if {@code maxLength} is less than the length of {@code
   *     truncationIndicator}
   * @since 16.0
   */

          int expected = (x < y) ? 1 : 0;
          int actual = LongMath.lessThanBranchFree(x, y);
          assertEquals(expected, actual);
        }
      }
    }
  }

  // Throws an ArithmeticException if "the simple implementation" of binomial coefficients overflows
  @GwtIncompatible // TODO
  private long simpleBinomial(int n, int k) {
    long accum = 1;
    for (int i = 0; i < k; i++) {

public class SystemHelperTest extends UnitFessTestCase {

    public SystemHelper systemHelper;

    private final Map<String, String> envMap = new HashMap<>();

    @Override
    protected void setUp(TestInfo testInfo) throws Exception {
        super.setUp(testInfo);
        final File propFile = File.createTempFile("project", ".properties");
        propFile.deleteOnExit();

    assertThat(converter.reverse().convert(0666L)).isEqualTo("438");
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testStringConverter_nullPointerTester() throws Exception {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(Longs.stringConverter());
  }

  public void testTryParse() {
    tryParseAndAssertEquals(0L, "0");

    assertThat(converter.reverse().convert((short) 0666)).isEqualTo("438");
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testStringConverter_nullPointerTester() throws Exception {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(Shorts.stringConverter());
  }

    assertThat(converter.reverse().convert(1e-6)).isEqualTo("1.0E-6");
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testStringConverter_nullPointerTester() throws Exception {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(Doubles.stringConverter());
  }

  @GwtIncompatible
  public void testTryParse_withNullNoGwt() {