Java 11 - ConcurrentModificationException with 1.2.0 update

[SlimeDog]

[07:52:08] [Server thread/INFO]: [BentoBox] Hooking with Vault...
[07:52:08] [Server thread/INFO]: [BentoBox] Hooking with PlaceholderAPI...
[07:52:08] [Server thread/INFO]: [BentoBox] Loading addons...
[07:52:08] [Server thread/ERROR]: [BentoBox] Skipping BSkyBlock due to an unhandled exception...
[07:52:08] [Server thread/ERROR]: [BentoBox] STACKTRACE: ConcurrentModificationException - null - null
[07:52:08] [Server thread/INFO]: [BentoBox] Loaded 2 addons.
[07:52:08] [Server thread/INFO]: [BentoBox] Enabling addons...
[07:52:08] [Server thread/ERROR]: [BentoBox] Skipping Challenges due to an unhandled exception...
[07:52:08] [Server thread/ERROR]: [BentoBox] STACKTRACE: ConcurrentModificationException - null - null
[07:52:08] [Server thread/ERROR]: [BentoBox] Skipping Level due to an unhandled exception...
[07:52:08] [Server thread/ERROR]: [BentoBox] STACKTRACE: ConcurrentModificationException - null - null
[07:52:08] [Server thread/INFO]: [BentoBox] Addons successfully enabled.

BentoBox/BSkyBlock is not running, despite "successfully enabled" above. Similar to (perhaps same as) #488, which was closed.

Steps to reproduce the behavior:

1. Download and install bentobox 1.2.0 and bskyblock 1.1
2. Edit configuration files as appropriate
3. Start server
4. See error

Server Information:

• Database being used: YAML
• OS: CentOS current
• Java Version: 11

>bentobox version
[07:58:00 INFO]: Bentobox version: 1.2.0
[07:58:00 INFO]: Loaded Game Worlds:
[07:58:00 INFO]: Loaded Add-Ons
[07:58:00 INFO]: BSkyBlock 1.1
[07:58:00 INFO]: Challenges 0.3.0
[07:58:00 INFO]: Level 0.2.0

[Lmmb74]

This bug only happens when using Java 10 & 11. BentoBox works fine when using Java 8. (I didn't try using Java 9 and it's a Non-LTS version so I guessed it was not worth trying [despite the fact that I tried Java 10 also being Non-LTS :V]).

[SlimeDog]

That's nice. But I am using Java 11. Please adjust appropriately, and many thanks.

[tastybento]

I'll have a look at it and see if it's something easy to fix.

[Poslovitch]

Fixing this is fine, but I definitely plan to move to Java 11 soon. The more time passes, the more I regret to not be able to use some of the features that were brought in Java 9, 10 and 11.

[tastybento]

Maybe, but when you look at the stats of what the servers use, you'll see it's 95% Java 8 still.

[Poslovitch]

Yep, but they won't move to Java 11 if not a single plugin incites them to.

[SlimeDog]

I'm all in favor, but please be aware that -- similar to servers still running Spigot 1.8.x and etc. -- that many plugins -- the entire Citizens/Denizen/Depenizen/Sentinel cluster, for example -- claim to still rely on Java 8. And many server operators do not have a choice, since they are beholden to service providers for their stacks. So, it's tricky.

Despite the fact that Java 11 and Spigot 1.13.x have been available since ... never mind. :)

[SlimeDog]

Among the minor issues here, the addons were not successfully enabled, as claimed in the log.

[tastybento]

This should be fixed for now.

[SlimeDog]

Confirmed fixed in BentoBox 1.2.1
No more ConcurrentModificationException with Java 11