private LuckPermsDefaultsMap tryInject() throws Exception {
        Objects.requireNonNull(DEFAULT_PERMISSIONS_FIELD, "DEFAULT_PERMISSIONS_FIELD");
        PluginManager pluginManager = this.plugin.getBootstrap().getServer().getPluginManager();

        if (!(pluginManager instanceof SimplePluginManager)) {
            this.plugin.getLogger().severe("PluginManager instance is not a 'SimplePluginManager', instead: " + pluginManager.getClass());
            this.plugin.getLogger().severe("Unable to inject LuckPerms Default Permission map.");
            return null;
        }

        Object map = DEFAULT_PERMISSIONS_FIELD.get(pluginManager);
        if (map instanceof LuckPermsDefaultsMap && ((LuckPermsDefaultsMap) map).plugin == this.plugin) {
            return null;
        }

        //noinspection unchecked
        Map<Boolean, Set<Permission>> castedMap = (Map<Boolean, Set<Permission>>) map;

        // make a new map & inject it
        LuckPermsDefaultsMap newMap = new LuckPermsDefaultsMap(this.plugin, castedMap);
        DEFAULT_PERMISSIONS_FIELD.set(pluginManager, newMap);
        return newMap;
    }
Injects a {@link LuckPermsDefaultsMap} info the {@link PluginManager}.
bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/server/InjectorDefaultsMap.java