Error writing null sequence_offset to JPA read_side_offsets

[raboof]

When using cassandra as the write side and JPA as the read side, offsets will be time_uuid offsets rather than sequence offsets, so we will write null into the sequence_offset of the read side offsets table. However, when using postgres, the null value appears to be incorrectly converted, reporting a type conversion error for the sequence_offset column: Expected bigint, actual bytea:

In com.lightbend.lagom.internal.javadsl.persistence.jpa.JpaReadSideImpl.postgresqlBindUpdateOffsetQuery:

Statement:

update "read_side_offsets" set "sequence_offset"=?,"time_uuid_offset"=? where "read_side_id"=? and "tag"=?;
insert into "read_side_offsets" ("read_side_id","tag","sequence_offset","time_uuid_offset") select ?,?,?,? where not exists (select 1 from "read_side_offsets" where "read_side_id"=? and "tag"=?)

Parameters:

{1=null, 2=3e921930-c2ea-11eb-b3a8-6bd0db76f94f, 3=return-receipt-query-offset, 4=ReceiptEvent, 5=return-receipt-query-offset, 6=ReceiptEvent, 7=null, 8=3e921930-c2ea-11eb-b3a8-6bd0db76f94f, 9=return-receipt-query-offset, 10=ReceiptEvent}

Since the sequence_offset will always be null when reading from cassandra, a workaround is to create the table with a sequence_offset column of type bytea:

CREATE TABLE read_side_offsets (
  read_side_id VARCHAR(255), tag VARCHAR(255),
  sequence_offset bytea, time_uuid_offset char(36),
  PRIMARY KEY (read_side_id, tag)
)

This is possibly similar to #1772