According to spatial reference of the map CoordinateConversion widget use a projection function of geometry service :
By default it is geometry service of ArcGIS Online, but possible to set client geometry service :
esriConfig.geometryServiceUrl = "....";
My questions are :
Solved! Go to Solution.
The likely reason is that the Projection class is a Large payload that the API team lets you decide if you want to load that heavy module. They do not assume that you want that amount out payload added to your app just because you are using the cordinateConversion widget. I don't believe that it is possible to specify that the widget uses the projection class instead of the default geomertyService.