docs: private void start(List<ValidationMessage> errors, WrapperElement resource, WrapperElement element, StructureDefinition profile, NodeStack stack) throws FHIRException {
      // profile is valid, and matches the resource name
      if (rule(errors, IssueType.STRUCTURE, element.line(), element.col(), stack.getLiteralPath(), profile.hasSnapshot(),
          "StructureDefinition has no snapshot - validation is against the snapshot, so it must be provided")) {
  			validateElement(errors, profile, profile.getSnapshot().getElement().get(0), null, null, resource, element, element.getName(), stack, false);
  
  			checkDeclaredProfiles(errors, resource, element, stack);
  
        // specific known special validations
        if (element.getResourceType().equals("Bundle"))
          validateBundle(errors, element, stack);
        if (element.getResourceType().equals("Observation"))
          validateObservation(errors, element, stack);
      }
    }