assertFalse(emptyOptional.isPresent());
        assertEquals("default", emptyOptional.orElse("default"));

        // Test that empty optional returns null instead of throwing
        assertNull(emptyOptional.orElse(null));
    }

    public void test_ofNullable_multipleTypesInSequence() {
        // Test multiple different types in sequence to ensure type safety

        closer.close();
      }
    } catch (Throwable expected) {
      assertThat(expected).isInstanceOf(IOException.class);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertNull(c3);

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whileClosingLastCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

    assertSame(toBeSupplied, objectSupplier.get()); // idempotent
  }

  public void testOfInstanceSuppliesNull() {
    Supplier<@Nullable Integer> nullSupplier = Suppliers.ofInstance(null);
    assertNull(nullSupplier.get());
  }

  @J2ktIncompatible
  @GwtIncompatible // Thread
  @SuppressWarnings("DoNotCall")
  public void testExpiringMemoizedSupplierThreadSafe() throws Throwable {

        assertEquals(exp, transformer.getFileName(url, Constants.UTF_8));
    }

    public void test_decodeUrl_null() throws Exception {
        final FessFileTransformer transformer = createInstance();
        assertNull(transformer.decodeUrlAsName(null, true));
    }

    public void test_getHost_ok() {
        String url, exp;
        final FessFileTransformer transformer = createInstance();

        url = "";

        closer.close();
      }
    } catch (Throwable expected) {
      assertThat(expected).isInstanceOf(IOException.class);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertNull(c3);

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whileClosingLastCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

            assertNotNull(helper.suggester());
        } catch (Exception e) {
            assertTrue(true);
        }
    }

    public void test_suggester() {
        try {
            assertNull(suggestHelper.suggester());
        } catch (Exception e) {
            assertTrue(true);
        }
    }

    public void test_setSearchStoreInterval() {
        long interval = 5L;

      assertEquals(Integer.valueOf(0), defaultConverter.convert("anything"));
      assertEquals("", defaultConverter.reverse().convert(123));
      assertNull(defaultConverter.convert(null));
      assertNull(defaultConverter.reverse().convert(null));
    }
  }

  public void testConverterDefaultValue() {
    new ConverterDefaultValueChecker().check();
  }

                }
              });
          executionThread.start();
        }
      };

  @Override
  protected final void tearDown() {
    tearDownStack.runTearDown();
    assertNull(
        "exceptions should not be propagated to uncaught exception handlers",
        thrownByExecutionThread);
  }

  public void testServiceStartStop() throws Exception {

    assertEquals(bimap1, bimap2);
    bimap2.inverse().put(Country.SWITZERLAND, Currency.FRANC);
    assertEquals(Country.SWITZERLAND, bimap2.get(Currency.FRANC));
    assertNull(bimap1.get(Currency.FRANC));
    assertFalse(bimap2.equals(bimap1));

    /* Test that it can be empty. */
    EnumBiMap<Currency, Country> emptyBimap = EnumBiMap.create(Currency.class, Country.class);

    Map<String, Integer> underlying = new HashMap<>();
    underlying.put("a", 1);
    Map<String, String> map = transformValues(underlying, Functions.toStringFunction());
    assertEquals("1", map.remove("a"));
    assertNull(map.remove("b"));
  }

  public void testTransformEqualityOfMapsWithNullValues() {
    Map<String, @Nullable String> underlying = new HashMap<>();
    underlying.put("a", null);
    underlying.put("b", "");