code: @Override
      public String getEtagValue() {
          final Instant lastModifiedDate = getLastModifiedDate();
  
          if (lastModifiedDate != null) {
              return sha1Hex(getPath() + lastModifiedDate.toEpochMilli());
          }
          return "";
      }
docs: /* (non-Javadoc)
  @see org.fcrepo.kernel.api.models.FedoraResource#getEtagValue()