docs: public String readAttributeAsFixedLengthString(String attributeName, int bufferSize)
              throws UnsupportedKerasConfigurationException {
          synchronized (Hdf5Archive.LOCK_OBJECT) {
              Attribute a = this.file.openAttribute(attributeName);
              String s = readAttributeAsFixedLengthString(a, bufferSize);
              a.deallocate();
              return s;
          }
      }