Damaging yourself whilst wearing Thorns will not produce the Thorns Prick sound

Damaging yourself whilst wearing Thorns enchanted armour will not produce the Thorns sound when you take damage.

Steps to Reproduce:
1) Wear thorns armour and shoot yourself
2) Look at subtitles as you take damage
3)When you get the death message "<player> was killed trying to hurt <player>", confirming that you took damage from thorns, you will notice that there was no subtitle or sound mentioning the "Thorns prick" damage