OptionalbaseOptionalbasemapThe Esri Basemap object being extended. This property can also be a string representing the ID of a well-known basemap, e.g. "streets". See https://developers.arcgis.com/javascript/latest/api-reference/esri-Map.html#basemap for a complete list.
OptionaldescriptionOptionalfailureOptionaliconOptionalidThe unique ID to assign to the entity. If not specified, one will be generated.
OptionalincludedOptionalisOptionalonOptionalreferenceOptionaltask
Properties that can be passed into the constructor for mapping/BasemapExtension!BasemapExtension.