like that ;)

Activator.java

package org.heater.test.service;

import com.google.inject.AbstractModule;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Module;
import org.heater.api.HeaterActivator;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;

import java.util.Hashtable;

public class Activator extends HeaterActivator {
    @Inject Injector injector;

    @Override
    public void start(BundleContext context) throws Exception {
        Hashtable<String, String> properties = new Hashtable<>();
        properties.put("Plugin", "Test");

        TestImpl test = injector.getInstance(TestImpl.class);

        context.registerService(TestService.class, test, properties);
    }

    @Override
    public void stop(BundleContext context) throws Exception {
        //the context will automatically unregister services
    }

    @Override
    public Module pluginModule() {
        return new AbstractModule() {
            @Override
            protected void configure() {
                bind(TestService.class).to(TestImpl.class).asEagerSingleton();
            }
        };
    }
}