@SuppressWarnings("unchecked")
    public SelfT addExternal(ClickHouseExternalTable table) {
        checkSealed();

        if (externalTables.add(ClickHouseChecker.nonNull(table, ClickHouseExternalTable.TYPE_NAME))) {
            resetCache();
        }

        return (SelfT) this;
    }
Adds an external table.

@param table non-null external table
@return the request itself
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseRequest.java