IdeaModel ideaModel = ideaPluginFor(project).getModel();
        IdeaProject projectModel = ideaModel.getProject();
        JavaVersion projectSourceLanguageLevel = IdeaModuleBuilderSupport.convertToJavaVersion(projectModel.getLanguageLevel());
        JavaVersion projectTargetBytecodeLevel = projectModel.getTargetBytecodeVersion();

        DefaultIdeaProject out = new DefaultIdeaProject()

            .setLanguageLevel(new DefaultIdeaLanguageLevel(languageLevel.getLevel()))
            .setJavaLanguageSettings(new DefaultIdeaJavaLanguageSettings()
                .setSourceLanguageLevel(IdeaModuleBuilderSupport.convertToJavaVersion(languageLevel))
                .setTargetBytecodeVersion(targetBytecodeVersion)
                .setJdk(DefaultInstalledJdk.current()));
    }

import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

@NonNullApi
public class IdeaModuleBuilderSupport {

    public static @Nullable JavaVersion convertToJavaVersion(@Nullable IdeaLanguageLevel ideaLanguageLevel) {
        if (ideaLanguageLevel == null) {
            return null;
        }
        String languageLevel = ideaLanguageLevel.getLevel();