*
     * @param key the property key.
     * @param defaultValue a default value.
     * @return The property value of the default value
     */
    public String getProperty(String key, String defaultValue) {
        if (this.get(key) != null) {
            return this.get(key);
        }
        return defaultValue;
    }

    @Override
    public Set<Entry<String, String>> entrySet() {

        }

        // Expose protected methods for testing
        public void testAddSystemProperty(List<String> cmdList, String name, String defaultValue, String appendValue) {
            super.addSystemProperty(cmdList, name, defaultValue, appendValue);
        }

        public void testAddFessConfigProperties(List<String> cmdList) {
            super.addFessConfigProperties(cmdList);
        }

	}

	// default value is function or null or blank (primary keys)
	field.DefaultValue = strings.TrimSpace(field.DefaultValue)
	skipParseDefaultValue := strings.Contains(field.DefaultValue, "(") &&
		strings.Contains(field.DefaultValue, ")") || strings.ToLower(field.DefaultValue) == "null" || field.DefaultValue == ""
	switch reflect.Indirect(fieldValue).Kind() {
	case reflect.Bool:
		field.DataType = Bool

      val defaultValue = chain.value()
      assertThat(isDefaultValue(chain.value())).isTrue()
      val withOverride = chain.withOverride(nonDefaultValue)
      assertThat(chain).isNotSameInstanceAs(withOverride)
      assertThat(isDefaultValue(withOverride.value())).isFalse()

      return if (isDefault) {
        val withDefault = withOverride.withOverride(defaultValue)

     *
     * @param keySuffix the key suffix (appended to getConfigPrefix() + ".")
     * @param defaultValue the default value
     * @return the configured or default value
     */
    protected int getConfigInt(final String keySuffix, final int defaultValue) {
        final String key = getConfigPrefix() + "." + keySuffix;

    assertEquals(false, Defaults.defaultValue(boolean.class).booleanValue());
    assertEquals('\0', Defaults.defaultValue(char.class).charValue());
    assertEquals(0, Defaults.defaultValue(byte.class).byteValue());
    assertEquals(0, Defaults.defaultValue(short.class).shortValue());
    assertEquals(0, Defaults.defaultValue(int.class).intValue());
    assertEquals(0, Defaults.defaultValue(long.class).longValue());

    assertEquals(false, Defaults.defaultValue(boolean.class).booleanValue());
    assertEquals('\0', Defaults.defaultValue(char.class).charValue());
    assertEquals(0, Defaults.defaultValue(byte.class).byteValue());
    assertEquals(0, Defaults.defaultValue(short.class).shortValue());
    assertEquals(0, Defaults.defaultValue(int.class).intValue());
    assertEquals(0, Defaults.defaultValue(long.class).longValue());

    }

    @Override
    public @Nullable V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
      if (Collections2.safeContains(backingSet(), key)) {
        @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
        K k = (K) key;
        return function.apply(k);
      } else {
        return defaultValue;
      }
    }

    @Override
    public @Nullable V remove(@Nullable Object key) {

        return delegate().get(key);
      }
    }

    @Override
    public @Nullable V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
      synchronized (mutex) {
        return delegate().getOrDefault(key, defaultValue);
      }
    }

    @Override
    public boolean isEmpty() {
      synchronized (mutex) {
        return delegate().isEmpty();
      }

					alterColumn = true
				}
			case schema.Bool:
				v1, _ := strconv.ParseBool(dv)
				v2, _ := strconv.ParseBool(field.DefaultValue)
				if v1 != v2 {
					alterColumn = true
				}
			case schema.String:
				if dv != field.DefaultValue && dv != strings.Trim(field.DefaultValue, "'\"") {
					alterColumn = true
				}
			default: