"Failed to create default core-configuration-file" because of plugins/BlueMap symlink

[ion1]

What I did / Steps to reproduce

I have all the static Minecraft files, including plugin jars, under one directory in a Docker image, and all the state/configuration data under another directory mounted from the host filesystem.

Unfortunately, PaperMC places both plugin jars and plugin state/configuration side by side under the plugins directory. To work around this, I have a file structure as follows:

/minecraft-static/plugins/foo.jar (file)
/minecraft-static/plugins/foo → ../../minecraft-dynamic/plugins/foo (symlink)
/minecraft-dynamic/plugins/foo (directory)

This has worked with every plugin I have installed so far, but BlueMap fails to start, saying:
[Craft Scheduler Thread - 3 - BlueMap/WARN]: Failed to create default core-configuration-file: java.nio.file.FileAlreadyExistsException: ../../minecraft-static/plugins/BlueMap

BlueMap uses createDirectories in BlueMapConfigs.java. According to the documentation it throws FileAlreadyExistsException "if dir exists but is not a directory". The fact that it does not handle the case where dir exists but is a symlink to an existing directory has been reported and deemed to be intentional behavior.

PaperMC itself has worked around this problem previously.

Expected result

I expect BlueMap to see that plugins/BlueMap is a writeable directory, just one behind a symlink.

Actual result

BlueMap fails to start, saying "Failed to create default core-configuration-file".

Context

BlueMap Version: BlueMap-3.4-spigot
Platform: PaperMC 1.19.2-207 in a Docker container on Linux

Log

[2022-10-13 05:28:03] [Craft Scheduler Thread - 3 - BlueMap/INFO]: Loading...
[2022-10-13 05:28:03] [Craft Scheduler Thread - 3 - BlueMap/WARN]: Failed to create default core-configuration-file: java.nio.file.FileAlreadyExistsException: ../../minecraft-static/plugins/BlueMap
[2022-10-13 05:28:03] [Craft Scheduler Thread - 3 - BlueMap/WARN]: 
################################
 There is a problem with your BlueMap setup!
 BlueMap tried to find this file, but it does not exist:
 ../../minecraft-static/plugins/BlueMap/core.conf
################################
[2022-10-13 05:28:03] [Craft Scheduler Thread - 3 - BlueMap/ERROR]: Failed to load!
java.io.IOException: de.bluecolored.bluemap.common.config.ConfigurationException
        at de.bluecolored.bluemap.common.plugin.Plugin.load(Plugin.java:326) ~[?:?]
        at de.bluecolored.bluemap.bukkit.BukkitPlugin.lambda$onEnable$0(BukkitPlugin.java:147) ~[?:?]
        at org.bukkit.craftbukkit.v1_19_R1.scheduler.CraftTask.run(CraftTask.java:101) [paper-1.19.2.jar:git-Paper-207]
        at org.bukkit.craftbukkit.v1_19_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:57) [paper-1.19.2.jar:git-Paper-207]
        at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) [paper-1.19.2.jar:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:?]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:?]
        at java.lang.Thread.run(Unknown Source) [?:?]
Caused by: de.bluecolored.bluemap.common.config.ConfigurationException
        at de.bluecolored.bluemap.common.config.ConfigManager.loadConfigFile(ConfigManager.java:87) ~[?:?]
        at de.bluecolored.bluemap.common.config.ConfigManager.loadConfig(ConfigManager.java:61) ~[?:?]
        at de.bluecolored.bluemap.common.config.BlueMapConfigs.loadCoreConfig(BlueMapConfigs.java:122) ~[?:?]
        at de.bluecolored.bluemap.common.config.BlueMapConfigs.<init>(BlueMapConfigs.java:44) ~[?:?]
        at de.bluecolored.bluemap.common.config.BlueMapConfigs.<init>(BlueMapConfigs.java:37) ~[?:?]
        at de.bluecolored.bluemap.common.plugin.Plugin.load(Plugin.java:113) ~[?:?]
        ... 7 more