I got a book in my Inventory, every time someone tried to read it he will be kicked out of game.
the error in the console:

[02:00:18] [Server thread/INFO]: 1337Zero[/79.207.201.82:50078] logged in with entity id 1436 at ([world] 215.3414886916949, 64.0, 273.4011264176181)
[02:00:18] Netty Server IO #1/ERROR: org.bukkit.craftbukkit.libs.com.google.gson.JsonSyntaxException: org.bukkit.craftbukkit.libs.com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 14
[02:00:18] Netty Server IO #1/ERROR: org.bukkit.craftbukkit.libs.com.google.gson.JsonSyntaxException: org.bukkit.craftbukkit.libs.com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 14
[02:00:18] [Server thread/INFO]: 1337Zero lost connection: Disconnected
[02:00:18] [Server thread/INFO]: left 1337Zero