[server/plugins/docs] document Plugin class

src/server/plugins/Plugin.js

@@ -8,6 +8,42 @@ const defaultConfigSchema = Joi.object({
   enabled: Joi.boolean().default(true)
 }).default();
 
+/**
+ * The server plugin class, used to extend the server
+ * and add custom behavior. A "scoped" plugin class is
+ * created by the PluginApi class and provided to plugin
+ * providers that automatically binds all but the `opts`
+ * arguments.
+ *
+ * @class Plugin
+ * @param {KbnServer} kbnServer - the KbnServer this plugin
+ *                              belongs to.
+ * @param {String} path - the path from which the plugin hails
+ * @param {Object} pkg - the value of package.json for the plugin
+ * @param {Objects} opts - the options for this plugin
+ * @param {String} [opts.id=pkg.name] - the id for this plugin.
+ * @param {Object} [opts.uiExports] - a mapping of UiExport types
+ *                                  to UI modules or metadata about
+ *                                  the UI module
+ * @param {Array} [opts.require] - the other plugins that this plugin
+ *                               requires. These plugins must exist and
+ *                               be enabled for this plugin to function.
+ *                               The require'd plugins will also be
+ *                               initialized first, in order to make sure
+ *                               that dependencies provided by these plugins
+ *                               are available
+ * @param {String} [opts.version=pkg.version] - the version of this plugin
+ * @param {Function} [opts.init] - A function that will be called to initialize
+ *                               this plugin at the appropriate time.
+ * @param {Function} [opts.config] - A function that produces a configuration
+ *                                 schema using Joi, which is passed as its
+ *                                 first argument.
+ * @param {String|False} [opts.publicDir=path + '/public']
+ *    - the public directory for this plugin. The final directory must
+ *    have the name "public", though it can be located somewhere besides
+ *    the root of the plugin. Set this to false to disable exposure of a
+ *    public directory
+ */
 module.exports = class Plugin {
   constructor(kbnServer, path, pkg, opts) {
     this.kbnServer = kbnServer;
@@ -18,7 +54,6 @@ module.exports = class Plugin {
     this.uiExportsSpecs = opts.uiExports || {};
     this.requiredIds = opts.require || [];
     this.version = opts.version || pkg.version;
-    this.externalCondition = opts.initCondition || _.constant(true);
     this.externalInit = opts.init || _.noop;
     this.getConfigSchema = opts.config || _.noop;
     this.init = _.once(this.init);