Spigot includes a registry for the `EntityType` class (`Registry.ENTITY_TYPE`). Thus, I expect:

```java
Bukkit.getRegistry(EntityType.class)
``` 
to return the registry... However, in practice (please forgive the kotlin code):
```kotlin
class RegistryValueSerializer<T : Keyed>
@JvmOverloads
constructor(
val clazz: Class<T>,
val isAllowWildcard: Boolean,
val registry: Registry<T> =
Bukkit.getRegistry(clazz)
?: throw IllegalArgumentException("Registry for $clazz does not exist."),
) : SimpleSerializer<List<T>> {
```
throws the error (implying that it returned null):
```
at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]
Caused by: java.lang.IllegalArgumentException: Registry for class org.bukkit.entity.EntityType does not exist.
at me.deecaad.core.file.simple.RegistryValueSerializer.<init>(RegistryValueSerializer.kt:23) ~[?:?]
at me.deecaad.core.file.simple.RegistryValueSerializer.<init>(RegistryValueSerializer.kt) ~[?:?]
at me.deecaad.weaponmechanics.weapon.damage.DamageModifier.serialize(DamageModifier.java:417) ~[?:?]
at me.deecaad.weaponmechanics.weapon.damage.DamageModifier.serialize(DamageModifier.java:35) ~[?:?]
at me.deecaad.core.file.FileReader.fillOneFile(FileReader.java:255) ~[?:?]
```

I rebuilt Spigot from BuildTools just an hour ago to make sure... Could this be a Spigot bug? I haven't looked at the Spigot internals for Registries yet.