@Nonnull
    public static <T extends CommandExecutor> T registerCommand(@Nonnull Plugin plugin, @Nonnull T command, @Nonnull String... aliases) {
        return registerCommand(plugin, command, null, null, null, aliases);
    }
Registers a CommandExecutor with the server

@param plugin the plugin instance
@param command the command instance
@param aliases the command aliases
@param <T> the command executor class type
@return the command executor
helper/src/main/java/me/lucko/helper/utils/CommandMapUtil.java