The Bukkit#getRegistry(Class) method contract specifies that it returns
null for unknown registry types. The current implementation however
requires the passed class to be mappable to a known registry key.
For types like Material, which have a SimpleRegistry in bukkit's
Registry interface, no server side registry exists and such the type
cannot be mapped to a registry key.
The commit correctly returns null for types that are not mappable to a
registry key instead of throwing a NullPointerException.
1b174804c7