docs: private Map buildObjectImage(PersistenceBroker broker) throws PersistenceBrokerException
      {
          Map imageMap = new HashMap();
          ClassDescriptor cld = broker.getClassDescriptor(getObject().getClass());
          //System.out.println("++++ build image: " + getObject());
          // register 1:1 references in image
          buildImageForSingleReferences(imageMap, cld);
          // put object values to image map
          buildImageForFields(imageMap, cld);
          // register 1:n and m:n references in image
          buildImageForCollectionReferences(imageMap, cld);
          return imageMap;
      }