public synchronized Map<String, PluginMetadata> getMetadataExtractedPlugins()
    {
        return Collections.unmodifiableMap(new TreeMap<>(this.pluginMetadata));
    }
Returns metadata for all extracted plugins, mapped by their canonical name.

The collection is alphabetically sorted, by plugin name.

Note that an <em>installed</em> plugin is not per definition an <em>extracted</em> plugin, and an extracted
plugin is not per definition a <em>loaded</em> plugin.  A plugin that's extracted might, for instance, fail to
load, due to restrictions imposed by its {@code minServerVersion} definition.

@return A collection of metadata (possibly empty, never null).
xmppserver/src/main/java/org/jivesoftware/openfire/container/PluginManager.java