declare namespace javax {
    namespace imageio {
        namespace metadata {
            /**
             * An interface to be implemented by objects that can determine the
             * settings of an <code>IIOMetadata</code> object, either by putting
             * up a GUI to obtain values from a user, or by other means.  This
             * interface merely specifies a generic <code>activate</code> method
             * that invokes the controller, without regard for how the controller
             * obtains values (<i>i.e.</i>, whether the controller puts up a GUI
             * or merely computes a set of values is irrelevant to this
             * interface).
             * <p> Within the <code>activate</code> method, a controller obtains
             * initial values by querying the <code>IIOMetadata</code> object's
             * settings, either using the XML DOM tree or a plug-in specific
             * interface, modifies values by whatever means, then modifies the
             * <code>IIOMetadata</code> object's settings, using either the
             * <code>setFromTree</code> or <code>mergeTree</code> methods, or a
             * plug-in specific interface.  In general, applications may expect
             * that when the <code>activate</code> method returns
             * <code>true</code>, the <code>IIOMetadata</code> object is ready for
             * use in a write operation.
             * <p> Vendors may choose to provide GUIs for the
             * <code>IIOMetadata</code> subclasses they define for a particular
             * plug-in.  These can be set up as default controllers in the
             * corresponding <code>IIOMetadata</code> subclasses.
             * <p> Alternatively, an algorithmic process such as a database lookup
             * or the parsing of a command line could be used as a controller, in
             * which case the <code>activate</code> method would simply look up or
             * compute the settings, call methods on <code>IIOMetadata</code> to
             * set its state, and return <code>true</code>.
             * @see IIOMetadata#setController
             * @see IIOMetadata#getController
             * @see IIOMetadata#getDefaultController
             * @see IIOMetadata#hasController
             * @see IIOMetadata#activateController
             */
            // @ts-ignore
            interface IIOMetadataController {
                /**
                 * Activates the controller.  If <code>true</code> is returned,
                 * all settings in the <code>IIOMetadata</code> object should be
                 * ready for use in a write operation.  If <code>false</code> is
                 * returned, no settings in the <code>IIOMetadata</code> object
                 * will be disturbed (<i>i.e.</i>, the user canceled the
                 * operation).
                 * @param metadata the <code>IIOMetadata</code> object to be modified.
                 * @return <code>true</code> if the <code>IIOMetadata</code> has been
                 *  modified, <code>false</code> otherwise.
                 * @exception IllegalArgumentException if <code>metadata</code> is
                 *  <code>null</code> or is not an instance of the correct class.
                 */
                // @ts-ignore
                activate(metadata: javax.imageio.metadata.IIOMetadata): boolean
            }
        }
    }
}