MacOS, Eclipse Unable to find a JRE installation (OpenJDK)

Hi, I've just installed OpenJDK and Eclipse on a Mac (Mojave), and in Terminal I got this:

$ java -version
openjdk version "13.0.2" 2020-01-14
OpenJDK Runtime Environment (build 13.0.2+8)
OpenJDK 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)

But in Eclipse, trying to run the Connect IQ Simulator I got this error in console:

Unable to find a JRE installation. Make sure you have a default JRE specified in the Java preferences.
Aborting launch due to failed build.

Having installed the OpenJDK version and not the Oracle one, I don't have a PrefPane in MacOS's System Preferences

How can I fix this problem?

Thanks