code: public CompletableFuture<PingTxnStatus> pingTxn(final String scope,
                                                      final String stream,
                                                      final UUID txId,
                                                      final long lease,
                                                      final OperationContext contextOpt) {
          final OperationContext context = getNonNullOperationContext(scope, stream, contextOpt);
          return pingTxnBody(scope, stream, txId, lease, context);
      }
docs: Transaction heartbeat, that increases transaction timeout by lease number of milliseconds.
  
  @param scope Stream scope.
  @param stream Stream name.
  @param txId Transaction identifier.
  @param lease Amount of time in milliseconds by which to extend the transaction lease.
  @param contextOpt       operational context
  @return Transaction metadata along with the version of it record in the store.