OptionallegendA string URL to a legend graphic for the layer.
OptionalnameA string containing a unique name for the layer.
OptionalqueryableBoolean specifying whether a layer is queryable or not.
OptionalshowBoolean specifying whether to display popup or not.
OptionaltitleA user-friendly string title for the layer that can be used in a table of contents.
A layer object may allow overrides on popup content and drawing behavior for individual layers of a web service.
See https://developers.arcgis.com/web-map-specification/objects/wmsLayer_layer/.