presto-main/src/main/java/io/prestosql/server/PluginManagerConfig.java/PluginManagerConfig/setInstalledPluginsDir
class PluginManagerConfig:    @Config("plugin.dir")
    public PluginManagerConfig setInstalledPluginsDir(File installedPluginsDir)
    {
        this.installedPluginsDir = installedPluginsDir;
        return this;
    }