dumpInstanceRoutes(print = true, url = null) {
        const instances = {}

        let urls = []
        if ( url === null ) {
            urls = Object.keys(this.instanceRouters)
        } else {
            urls = [url]
        }

        // Get each uibuilder instance's routes
        urls.forEach( (url) => {
            instances[url] = []
            for ( const layer of this.instanceRouters[url].stack) { this.summariseRoute(layer, instances[url]) }
            if ( instances[url].length === 0 ) instances[url] = [{ name: 'No routes', }]
        })

        if (print) {
            console.log(' \n---- Per-Instance Client Facing Routes ----')

            Object.keys(this.instanceRouters).forEach( (url) => {
                console.log(`>> User Instance Routes ${this.uib.nodeRoot}/${url}/* >>`)
                console.table(instances[url])
            })
        }

        return instances
    }
Return a summary of all the ExpressJS routes for a specific uibuilder instance & output to console if required
@param {boolean} print If true, output to console
@param {string|null} [url] Optional. If not null, only dump the given instance
@returns {any} Summary object