Most DOORS Modules are configured to create an Object descriptor that indicates the type of artifact. In this case the DOORS module uses "Object Type".
This allows us in the mapping to both define that the attribute used on DOORS artifacts is "Object Type" as well as then map these values to the DOORS Next Artifact type we want.
We can see this configuration as well as a default DOORS Next Artifact Type defined.
The full mapping the Requirement Types then occurs by a simple attribute mapping to DOORS Next types.
Other things to note here.
__heading' is an override for objects presented in DOORS as a heading should always be a heading in DOORS Next independent of the mapping.
The result is a nice clean mapping and hierarchy.