Don't allow more required slices than max cardiniality of intro

[mmsmits]

Example:

<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="obs-5"/>
  <url value="urn:uuid:9a788a05-e881-4c0c-a3e7-cce309aab2d7"/>
  <name value="Obs5"/>
  <status value="draft"/>
  <description value="fixture for FirelyTeam/firely-net-sdk#1: closed slicing on polymorphic"/>
  <kind value="resource"/>
  <abstract value="false"/>
  <type value="Observation"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation"/>
  <derivation value="constraint"/>
  <differential>
    <element>
      <path value="Observation.value[x]"/>
      <slicing>
        <rules value="open"/>
      </slicing>
    </element>
    <element>
      <path value="Observation.value[x]"/>
      <sliceName value="valueCodeableConcept"/>
      <min value="1"/>
      <type>  
        <code value="CodeableConcept"/>
      </type>
      <binding>
        <strength value="required"/>
        <valueSet value="http://somewhere/something"/>
      </binding>
    </element>
    <element>
      <path value="Observation.value[x]"/>
      <sliceName value="valueQuantity"/>
      <type>  
        <code value="Quantity"/>
      </type>
      <binding>
        <strength value="required"/>
        <valueSet value="http://somewhere/something"/>
      </binding>
    </element>
  </differential>
</StructureDefinition>

In the example above, two slices are introduced. One has min cardinality of 1. However, observation.value[x] has a max card of 1. And a second slice therefor shouldn't be allowed. Should the snapshotgenerator throw an error when when this occurs? Or leave it up to the validator or other tooling to notice these things?

[mmsmits]

This one is for the validator

[ewoutkramer]

This is an enterprise validation on StructureDefinition.