@Override public CheckResult check() {
    if (closeCalled) throw new ClosedComponentException();
    try {
      session.healthCheck();
    } catch (Throwable e) {
      Call.propagateIfFatal(e);
      return CheckResult.failed(e);
    }
    return CheckResult.OK;
  }
{@inheritDoc} Memoized in order to avoid re-preparing statements
zipkin-storage/cassandra/src/main/java/zipkin2/storage/cassandra/CassandraStorage.java