well, just 3 options, explicit name of renderer class, renderer function in renderer proprty or ignore the property and sap.ui.core.ElementMetadata will do the job for you:
// remove renderer stuff before calling super.
var vRenderer = oClassInfo.hasOwnProperty("renderer") ? (oClassInfo.renderer || "") : undefined;
delete oClassInfo.renderer;
sap.ui.base.ManagedObjectMetadata.prototype.applySettings.call(this, oClassInfo);
this._sRendererName = this.getName() + "Renderer";
if ( typeof vRenderer !== "undefined" ) { if ( typeof vRenderer === "string" ) { this._sRendererName = vRenderer || undefined; return; } if ( typeof vRenderer === "function" ) { vRenderer = { render : vRenderer }; }
...
}