public ClickHouseInputStream getInputStream() {
        return input != null ? ClickHouseInputStream.of(input) : ClickHouseInputStream.empty();
    }
Gets the input stream for reading. Please pay attention that the returned
input stream has nothing to do with this pass-thru stream, as
{@code getInputStream().getUnderlyingStream()} is always {@link #NULL}.

@return non-null input stream
clickhouse-data/src/main/java/com/clickhouse/data/ClickHousePassThruStream.java