docs: public String readAttributeAsJson(String attributeName, String... groups)
              throws UnsupportedKerasConfigurationException {
          synchronized (Hdf5Archive.LOCK_OBJECT) {
              if (groups.length == 0) {
                  Attribute a = this.file.openAttribute(attributeName);
                  String s = readAttributeAsJson(a);
                  a.deallocate();
                  return s;
              }
              Group[] groupArray = openGroups(groups);
              Attribute a = groupArray[groups.length - 1].openAttribute(attributeName);
              String s = readAttributeAsJson(a);
              a.deallocate();
              closeGroups(groupArray);
              return s;
          }
      }