Pocketmine-mp: Resource pack with metadata entry in manifest.json does not load

[thebigsmileXD]

Issue description

• Expected result: Pack loads
• Actual result: [Server thread/CRITICAL]: Could not load resource pack "nethergames.zip": manifest.json is missing required fields

Steps to reproduce the issue

1. Create a dummy resource pack
2. Add format_version, header and modules to manifest.json
3. Load server : success
4. Add optional metadata to manifest.json
5. Pack does not load

Code that causes the issue

https://github.com/pmmp/PocketMine-MP/blob/master/src/resourcepacks/json/Manifest.php
is missing optional metadata
https://github.com/pmmp/PocketMine-MP/blob/70b0d832583c162484458e1ef4dbc70c174ea7b4/src/resourcepacks/ZippedResourcePack.php#L111-L116
Throws misleading error ("missing required fields" at any time)
https://github.com/pmmp/PocketMine-MP/blob/70b0d832583c162484458e1ef4dbc70c174ea7b4/src/resourcepacks/ZippedResourcePack.php#L113
Can not map successfully and throws JsonMapper_Exception if additional fields are provided

OS and versions

• PocketMine-MP: PocketMine-MP 4.0.0+dev for Minecraft: Bedrock Edition v1.16.100 (protocol version 419)
• PHP: 7.4
• Server OS: Win10

Plugins

Plugins (4): DEVirion v1.2.5-ALPHA13, DevTools v1.15.0+dev, FormImagesFix v0.0.1, xendevtools2 v0.0.0

• If you remove all plugins, does the issue still occur? Yes

Crashdump, backtrace or other files

[dktapps]

Is the metadata field an officially accepted thing? There's no spec on this stuff so I'm never sure.

[ZizzyZizzy]

Yup

https://minecraft.gamepedia.com/Bedrock_Edition_add-on_documentation

[dktapps]

Thanks, I didn't know that documentation existed.

[dktapps]

Fixed by 07dc0f2dd56c07b3c52e6bec976e12ad8b071250.