code: void validateBackend(EntityType entityType) {
      // Validate backend exists
      String backendName = entityType.getBackend();
      if (!dataService.getMeta().hasBackend(backendName)) {
        throw new MolgenisValidationException(
            new ConstraintViolation(format("Unknown backend [%s]", backendName)));
      }
    }
docs: Validate that the entity meta data backend exists
  
  @param entityType entity meta data
  @throws MolgenisValidationException if the entity meta data backend does not exist