There are actually a number of problems here.
First, you’re registering a command every time a player joins. This is a Bad Thing. You should be registering commands in initialization.
Second, looking at your command executor code, you’re calling
toString on arguments. The intended way would just be to include a type parameter in
getOne, such as
<String>. What you’re doing could turn into a Bad Thing if you use it in places that aren’t strings.
Third, you’re sending “Please register with /register” regardless of whether the command was successful or not.
Also, saying that it says something but you don’t know what it says is completely useless. Please post exactly what it says.
The real problem here is your import statement:
You need to be using Sponge’s
Getter, not the JDK internals.