"error: cannot find symbol import com.liferay.portal.kernel.uuid.PortalUUID;" in Liferay 7.4

I am working with Liferay portal-7.4-ga107 (with IntelliJ) and trying to do a training guestbook app following this tutorial from Liferay. I have followed it perfectly and even repeated the process 3 times, but at the end of the "Integrating the Back-end" step I always encounter this error right after deploying the module/portlet:

error: cannot find symbol
import com.liferay.portal.kernel.uuid.PortalUUID;
                                     ^
  symbol:   class PortalUUID
  location: package com.liferay.portal.kernel.uuid

The error seems to be directly related to this dependency in the persistence classes (which are auto-generated in the process):

import com.liferay.portal.kernel.uuid.PortalUUID; //(highlighted as red in code)

Inside the persistence classes, PortalUUID is only "used" here:

    @Reference
    private PortalUUID _portalUUID;

and here:

    String uuid = _portalUUID.generate();

I've done a lot of research and tried a few things, with no luck. The error could be related to something that is outdated and I haven't found, or a change in PortalUUID for my version, I really don't know.

I'm using JDK 8 and gradle 6.9.2

Any help is appreciated, thanks in advance.

Relevant attempts:

I tried to deploy my portlet guestbook-web after finishing this step from the Liferay tutorial, I expected it to get built successfully, but the kernel.uuid.PortalUUID dependency error appeared.

Afterwards, I tried replacing PortalUUID with PortalUUIDUtil, this last one didn't cause any errors in the code, but after deploying the module (guestbook-web), it didn't appear in the portal.

Finally, I saw in Liferay docs that PortalUUIDUtil has a getPortalUUID() method, I tried using PortalUUIDUtil.getPortalUUID(); with no luck (the method doesn't even exist according to my IDE).

Liferay 7.4 (after GA/U 100) requires the workspace version 9.0.4 or higher to generate ServiceBuilder code adapted to the changed PortalUUID API.

Make sure to configure your Liferay workspace at least like this in your settings.gradle:

dependencies {   
    classpath group: “com.liferay”, 
              name: “com.liferay.gradle.plugins.workspace”, 
              version: “9.0.4"
}