docs: public Map<String, Object> getObjectReferenceMap(String field, String schemaName) {
          List<String> instanceIds = references.get(field);
          if(instanceIds == null || instanceIds.size() == 0) {
              return null;
          }
          Map<String, Object> objects = new HashMap<>();
          for (String instanceId : instanceIds) {
              BeanId id = BeanId.create(instanceId, schemaName);
              Object instance = instances.get(id);
              if(instance != null) {
                  objects.put(instanceId, instance);
              } else {
                  instance = cache.get(id);
                  instances.put(id, instance);
                  objects.put(instanceId, instance);
              }
          }
          return objects;
      }