@SuppressWarnings("serial") // never serialized
  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
          }
        };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

    for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
      /*
       * requireNonNull is safe because propertyNames contains only non-null elements.
       *
       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our

    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

    for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
      /*
       * requireNonNull is safe because propertyNames contains only non-null elements.
       *
       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our

        @Override
        public void doValidate(String propertyName, Object value, PropertyValidationContext context) {
        }

        @Override
        public void validate(String propertyName, Supplier<Object> propertyValue, PropertyValidationContext context) {
        }
    },
    INPUT_FILE_VALIDATOR("file") {
        @Override
        public void doValidate(String propertyName, Object value, PropertyValidationContext context) {

        writeNextProperty(propertyName, propertyValue, kind)
    }

    suspend fun writeInputProperty(propertyName: String, propertyValue: Any?) =
        writeProperty(propertyName, propertyValue, PropertyKind.InputProperty)

    suspend fun writeOutputProperty(propertyName: String, propertyValue: Any?) =
        writeProperty(propertyName, propertyValue, PropertyKind.OutputProperty)

        if (value != null) {
            System.setProperty(propertyName, value);
        } else {
            System.clearProperty(propertyName);
        }
        return originalValue;
    }

    private void restoreProperty(String propertyName, @Nullable String originalValue) {
        if (originalValue != null) {
            System.setProperty(propertyName, originalValue);
        } else {

    private final Class<?> targetClass;

    private final String propertyName;

    /**
     * {@link PropertyNotFoundRuntimeException}を返します。
     *
     * @param targetClass
     *            ターゲットクラス
     * @param propertyName
     *            プロパティ名
     */
    public PropertyNotFoundRuntimeException(final Class<?> targetClass, final String propertyName) {
        super("ECL0065", asArray(targetClass.getName(), propertyName));

        return __modifiedProperties.getPropertyNames();
    }

    public void mymodifyProperty(String propertyName) {
        registerModifiedProperty(propertyName);
    }

    public void mymodifyPropertyCancel(String propertyName) {
        __modifiedProperties.remove(propertyName);
    }

    public void clearModifiedInfo() {
        __modifiedProperties.clear();
    }

        }

        @Override
        public TypeValidationDataSpec pluginId(String pluginId) {
            this.pluginId = pluginId;
            return this;
        }

        @Override
        public TypeValidationDataSpec propertyName(String propertyName) {
            this.propertyName = propertyName;
            return this;
        }

        return __modifiedProperties.getPropertyNames();
    }

    public void mymodifyProperty(String propertyName) {
        registerModifiedProperty(propertyName);
    }

    public void mymodifyPropertyCancel(String propertyName) {
        __modifiedProperties.remove(propertyName);
    }

    public void clearModifiedInfo() {
        __modifiedProperties.clear();
    }