@Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD}) 
@Retention(RetentionPolicy.RUNTIME)
public @interface Extension
{
    /** Vendor that the extension applies to (required).
     * @return the vendor
     */
    String vendorName();

    /** The key for the extension (required). 
     * @return the key
     */
    String key();

    /** The value for the extension (required). 
     * @return the value
     */
    String value();
}