code: private ImmutableMap<CQIE, PPMappingAssertionProvenance> convertIntoDatalog(SQLPPMapping ppMapping, RDBMetadata dbMetadata)
              throws InvalidMappingSourceQueriesException {
  
          /*
           * May also add views in the DBMetadata!
           */
          ImmutableMap<CQIE, PPMappingAssertionProvenance> datalogMap = ppMapping2DatalogConverter.convert(
                  ppMapping.getTripleMaps(), dbMetadata);
  
          LOGGER.debug("Original mapping size: {}", datalogMap.size());
  
          // Normalizing language tags and equalities (SIDE-EFFECT!)
          normalizeMapping(datalogMap.keySet());
  
          return datalogMap;
      }
docs: Assumption: one CQIE per mapping axiom (no nested union)