CombatLog Plugin (1.12.2) – Bukkit, Spigot, Paper - 9Minecraft.Net
Combat Plugin | SpigotMC - High Performance Minecraft
Anti Combat Logging | SpigotMC - High Performance Minecraft
GitHub - SirBlobman/CombatLogX: A modular Spigot plugin that prevents players from logging out during combat and has many expansions for extra features.