code: @Override
      public long getSize() {
          switch (keyMode) {
          case HASH:
              try {
                  return getJedis().hlen(getName());
              } catch (Exception e) {
                  throw e instanceof CacheException ? (CacheException) e : new CacheException(e);
              }
          default:
              return -1;
          }
      }
docs: {@inheritDoc}
  
  <p>
  Only {@link KeyMode#HASH} is supported. This method returns {@code -1}
  for other key modes.
  </p>