public byte[] toByteArray() {
        byte[] result = new byte[count];
        System.arraycopy(buf, 0, result, 0, count);
        return result;
    }
returns inner array

@return the current contents of this output stream, as a byte array.
clickhouse-data/src/main/java/com/clickhouse/data/format/tsv/FastByteArrayOutputStream.java