Domain Map Swap the preloaded values

[MikeMillerGIS]

For the domain map, we should preload the source side instead of the target side. This would eliminate the issue of setting the same source value to different target values

example of a bad mapping:

@SteveGrise @JRosenfeldIntern

[JRosenfeldIntern]

This was merged, can close the issue @MikeMillerGIS