Service Builder: Cannot find symbol *LocalService for referenced entity

Issue

After targeting a more recent version of the product, you may get a 'cannot find symbol' error for an injected @Reference in your FooLocalServiceBaseImpl class. Something like this:
```
error: cannot find symbol
    protected com.liferay.asset.kernel.service.AssetLinkLocalService
```

For this example, your entity's service.xml would look like this:

<reference entity="AssetLink" package-path="com.liferay.portlet.asset" />

Environment

Liferay Workspace

Resolution

This can happen if the referenced entity has been moved to a diferent package (likely from the kernel to an OSGi module).
You can check if that's your case by searching for the referenced entity in the project code.
If that is your case, you can follow the following approach:
- Remove that <reference> from your entity's service.xml.
- Instead, reference the desired *LocalService class from your FooLocalServiceImpl using the @Reference annotation.
- This is what has been done internally in the product. If we use the AssetLink modularization as an example:
  - It was implemented in LPS-139732.
  - <reference>s were removed by this commit.
  - @References were added to *LocalServiceImp classes in this commit.

Note that you will get the following error in case you just change the package-path for the new one:

Unable to find AssetLink in Foo
Exception in thread "main" com.liferay.portal.tools.service.builder.ServiceBuilderException: Unable to find AssetLink in Foo
  at com.liferay.portal.tools.service.builder.ServiceBuilder.getEntity(ServiceBuilder.java:1244)
  at com.liferay.portal.tools.service.builder.ServiceBuilder._resolveEntity(ServiceBuilder.java:8000)
  at com.liferay.portal.tools.service.builder.ServiceBuilder.<init>(ServiceBuilder.java:805)
  at com.liferay.portal.tools.service.builder.ServiceBuilder.main(ServiceBuilder.java:234)
Caused by: java.io.IOException: Unable to open resource com/liferay/asset/link/service.xml in class loader sun.misc.Launcher$AppClassLoader@1b6d3586
  at com.liferay.portal.kernel.util.StringUtil.read(StringUtil.java:2286)
  at com.liferay.portal.kernel.util.StringUtil.read(StringUtil.java:2254)
  at com.liferay.portal.tools.service.builder.ServiceBuilder.getEntity(ServiceBuilder.java:1239)

You can use another approach too, described in this other article.

Additional Information

Reference tag in service builder service.xml is not allowing to have MBMessage reference