Can't initiate working with OpenNTF Domino API, what am I doing wrong?

Question

I am working with DDE version: Release 10.0.1FP4

Then I downloaded from OpenNTF the 6 mei 2019 10.0.1 version of ODA. installation in DDE went fine.

On my nsf in the xsp.properties I referenced the plugin as a dependency:

xsp.library.depends=org.openntf.domino.xsp.XspLibrary

Then I created my first java class:

package se.acme.oda;

public class HelloWorld {   
    private void tryMe(){       
        Session sess = Factory.getSession(SessionType.CURRENT);
        Database db = sess.getDatabase("", "database.nsf", true);       
    }
}

When I build my project I get the following errors:

• Database cannot be resolved to a type
• Factory cannot be resolved
• Session cannot be resolved to a type
• SessionType cannot be resolved to a variable

Can someone guide me through the process of starting to use the ODA plugin?

Should I import the library in my java class or? (tried but did not help). Looks like it can not find the installation?