code: List<Attribute> getAlgorithmSourceAttributes(
        Entity attributeMappingEntity, EntityType sourceEntityType) {
      List<Attribute> attributes;
  
      String sourceAttributesString = attributeMappingEntity.getString(SOURCE_ATTRIBUTES);
      if (sourceAttributesString != null) {
        attributes = new ArrayList<>();
        for (String sourceAttributeStr : sourceAttributesString.split(",")) {
          Attribute sourceAttribute = sourceEntityType.getAttribute(sourceAttributeStr);
          if (sourceAttribute != null) {
            attributes.add(sourceAttribute);
          }
        }
      } else {
        attributes = emptyList();
      }
      return attributes;
    }
docs: Returns attributes for the source attribute names in the given entity. Ignores attribute names
  for which no attribute exists in the source entity type due to (see
  https://github.com/molgenis/molgenis/issues/8051).
  
  <p>package-private for testability