This new column is of type timestamp and nullable. It needs to be updated with now() every time we create/update a remittance entity.
For doing this, we can use the "@PrePersist" and "@PreUpdate" annotations like:

@PreUpdate @PrePersist
  public void prePersist() {
    this.updatedAt = OffsetDateTime.now(ZoneId.of("UTC"));
  }

We don't need to update the existing records.
About tests, we can assert that the new records contain the updated_at column with a timestamp populated.