PearlXP

This enables enderpearls to store experience, to safeguard XP from deaths and to allow trading XP like physical items.
Features

• Left clicking with an enderpearl in hand deposits up to 16 (configurable) levels worth of experience into the pearl, making it look like an Eye of Ender
• Left clicking with an imbued Eye restores the experience and returns a plain pearl
• Experience lost/gained still takes level scaling into account (from wiki's values)
  • For example, with the cap set at 10, up to 160 xp can be stored
  • If at level 16, storing 160xp (the xp to get from level 0->10) will take you to 11.4
  • If at level 10, storing 160xp will take you to 0
  • If at level 20, restoring 160xp will take you to 22.4
• Right clicking imbued Eyes tells you how much XP is in them and won't throw them, as that'd waste the XP
• Imbued pearls (Eyes of Ender with a custom name + lore) can be dropped on the ground and left in chests, including through server restarts
• /pearlxp <level> imbues the held pearl with a specific number of levels

UltiByte made a video of v1.3.4 (missing the new custom imbued pearl name/description, but you get the idea)

Configuration

• maxLevel - The max experience that can be stored in a single pearl (so maxlevel 16 would be the experience from level 0->16, or 352xp)
• emptyMaterial - The item material to use for the "empty pearl".
• imbuedMaterial - The item material to use for the imbued pearl, can be the same as the empty pearl
• expReturnRate - A multiplier for how much experience to return to the player on restore. 0.85 would impose a 15% "penalty" or "tax"
• alwaysBlockRightClick - Default off, entirely disables enderpearl/eye teleportation (not just on imbued stuff)
• Customizable Messages

Permissions

• pearlxp.imbue - Default true
• pearlxp.restore - Default true

The source code is in the jar.
Tested on Spigot 1.13.2