Forge api is not added to a new project

Hello, I have the latest versions of jdk, jre and gradle installed for sure. Also, I have the required forge version installed (in the .minecraft folder there is a file forge-1.12.2-14.23.5.2854.jar). Next, I unpack the forge-mdk archive, go to the console at the location of the unpacked file and run the genEclipseRuns command. Then I go into Eclipse and import that folder as a gradle project. And here the most interesting thing begins, in the folder with the example of the mod everything is underlined in red, since the dependencies on the net.minecraft. * Package are broken - there is simply no such package! I looked on YouTube, there the guy (in the package manager) has a referenced package under the jre system library package, I don't have such a package, that's why all the dependencies are broken. Something went wrong?
I am using Windows 10, Eclipse and Minecraft 1.12.2