Email template variable naming prevent DRY

[sldblog]

Short problem statement; why is this a problem?

Variables in our email templates are not consistent.
This leads to unnecessary code duplication.

This leads to dealing with errors like EventException: NullPointerException: null; while processing ReferralEvent more difficult (there's no assignee).

Link to different approaches

With camelCase:

hmpps-interventions-service/src/main/kotlin/uk/gov/justice/digital/hmpps/hmppsinterventionsservice/service/notifications/ReferralNotificationService.kt

Lines 71 to 73 in bf2b251

	"spFirstName" to userDetails.firstName,
	"referenceNumber" to event.referral.referenceNumber!!,
	"referralUrl" to location.toString(),

With snake_case:

hmpps-interventions-service/src/main/kotlin/uk/gov/justice/digital/hmpps/hmppsinterventionsservice/service/notifications/ReferralNotificationService.kt

Lines 85 to 87 in bf2b251

	"sp_first_name" to userDetails.firstName,
	"referral_number" to event.referral.referenceNumber!!,
	"referral" to location.toString()

Do you have a proposed solution? Why?

Standardise on one casing. Use it everywhere.

This requires duplicating templates until the switchover happens.

[sldblog]

#1219 partially DRYs the code up, but there are still templates with different casing and names for the same values.