A generic user-implemented mapping method matched any source/target type pair during mapping resolution, which happens before the Use= named mapping reference is resolved. As a result a generic method (e.g. T Identity(T)) shadowed mappings that were explicitly referenced via Use on individual members.

Generic template matching is now skipped when a mapping is explicitly referenced by name, letting the UseNamedMappingBuilder resolve it. The named mapping builder also instantiates a concrete mapping when a generic method is referenced by name directly.

Closes #2277

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