*
     * @return an enumeration of all the keys in this property list, including the keys in the default property list.
     */
    public Enumeration<?> propertyNames() {
        return Collections.enumeration(storage.keySet());
    }

    /**
     * Calls the map method put. Provided for parallelism with the getProperty method.

     *
     * @return an enumeration of all the keys in this property list, including the keys in the default property list.
     */
    public Enumeration<?> propertyNames() {
        return Collections.enumeration(storage.keySet());
    }

    /**
     * Calls the map method put. Provided for parallelism with the getProperty method.

  @GwtIncompatible // Maps.fromProperties
  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(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

        super("ECL0059", asArray(targetClass.getName(), propertyName, cause), cause);
        this.targetClass = targetClass;
        this.propertyName = propertyName;
    }

    /**
     * Returns the target class.
     *
     * @return Target class
     */
    public Class<?> getTargetClass() {
        return targetClass;
    }

    /**

        return __modifiedProperties.getPropertyNames();
    }

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

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

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

        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 boolean hasPropertyDesc(final String propertyName) {
        assertArgumentNotEmpty("propertyName", propertyName);

        return propertyDescCache.get(propertyName) != null;
    }

    @Override
    public PropertyDesc getPropertyDesc(final String propertyName) {
        assertArgumentNotEmpty("propertyName", propertyName);

        final PropertyDesc pd = propertyDescCache.get(propertyName);

     */
    private final String propertyName;

    /**
     * Returns a {@link PropertyNotFoundRuntimeException}.
     *
     * @param targetClass the target class
     * @param propertyName the property name
     */
    public PropertyNotFoundRuntimeException(final Class<?> targetClass, final String propertyName) {
        super("ECL0065", asArray(targetClass.getName(), propertyName));
        this.targetClass = targetClass;