// different value
    assertThat(segment.replace(key, hash, oldValue, newValue)).isFalse();
    assertThat(segment.count).isEqualTo(1);
    assertThat(segment.get(key, hash)).isSameInstanceAs(newValue);

    // cleared
    entry.setValueReference(oldValueRef);
    assertThat(segment.get(key, hash)).isSameInstanceAs(oldValue);
    oldValueRef.clear();

    // different value
    assertThat(segment.replace(key, hash, oldValue, newValue)).isFalse();
    assertThat(segment.count).isEqualTo(1);
    assertThat(segment.get(key, hash)).isSameInstanceAs(newValue);

    // cleared
    entry.setValueReference(oldValueRef);
    assertThat(segment.get(key, hash)).isSameInstanceAs(oldValue);
    oldValueRef.clear();

        V value = localCache.get(key);
        if (value != null) {
          return value;
        }

        try {
          V newValue = valueLoader.call();
          // TODO(b/147136275): Perform a null check on the result.
          localCache.put(key, newValue);
          return newValue;
        } catch (Exception e) {
          throw new ExecutionException(e);
        }
      }
    }

    @Override

    Integer oldValue = map.putInstance(Integer.class, new Integer(7));
    assertEquals(5, (int) oldValue);

    Integer newValue = map.getInstance(Integer.class);
    assertEquals(7, (int) newValue);

    // Won't compile: map.putInstance(Double.class, new Long(42));
  }

  public void testNull() {

            String value1 = fessConfig.get(testKey);
            assertEquals(initialValue, value1);

            // Change system property
            String newValue = "changed";
            System.setProperty(Constants.FESS_CONFIG_PREFIX + testKey, newValue);

            // Get value again - in real FessConfigImpl it would be cached,
            // but our test implementation always checks system properties

    }

    @Override
    @Nullable V getValue(int index) {
      return at(index, columnIndex);
    }

    @Override
    @Nullable V setValue(int index, @Nullable V newValue) {
      return set(index, columnIndex, newValue);
    }
  }

  /**
   * Returns an immutable set of the valid column keys, including those that are associated with
   * null values only.
   *

           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,
        EnumMapAccumulator::toImmutableMap,

           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,
        EnumMapAccumulator::toImmutableMap,

   */
  final void checkNoDuplicate(R rowKey, C columnKey, @Nullable V existingValue, V newValue) {
    checkArgument(
        existingValue == null,
        "Duplicate key: (row=%s, column=%s), values: [%s, %s].",
        rowKey,
        columnKey,
        newValue,
        existingValue);
  }

  // redeclare to satisfy our test for b/310253115
  @Override
  @J2ktIncompatible

        assertEquals(true, builder.initialSettings.get("key3"));

        // Test overwriting existing setting
        builder.addInitialSettings("key1", "newValue1");
        assertEquals(3, builder.initialSettings.size());
        assertEquals("newValue1", builder.initialSettings.get("key1"));
    }

    @Test
    public void testAddInitialSettingsWithNullValue() {
        // Test adding null value