then:
        ideaProject.javaLanguageSettings.targetBytecodeVersion == JavaVersion.VERSION_1_5
        ideaProject.modules.find { it.name == 'root' }.javaLanguageSettings.targetBytecodeVersion == null
        ideaProject.modules.find { it.name == 'child1' }.javaLanguageSettings.targetBytecodeVersion == null
        ideaProject.modules.find { it.name == 'child2' }.javaLanguageSettings.targetBytecodeVersion == null

        ideaProject.javaLanguageSettings.targetBytecodeVersion == JavaVersion.VERSION_1_5
        ideaProject.modules.find { it.name == 'test-project' }.javaLanguageSettings.targetBytecodeVersion == null
        ideaProject.modules.find { it.name == 'child1' }.javaLanguageSettings.targetBytecodeVersion == null
        ideaProject.modules.find { it.name == 'child2' }.javaLanguageSettings.targetBytecodeVersion == null
    }

    private JavaVersion languageLevel;
    private JavaVersion targetBytecodeVersion;
    private DefaultInstalledJdk jdk;

    public DefaultIdeaJavaLanguageSettings setSourceLanguageLevel(JavaVersion languageLevel) {
        this.languageLevel = languageLevel;
        return this;
    }

    public DefaultIdeaJavaLanguageSettings setTargetBytecodeVersion(JavaVersion targetBytecodeVersion) {
        this.targetBytecodeVersion = targetBytecodeVersion;

        then:
        subprojectA.javaSourceSettings.targetBytecodeVersion == JavaVersion.VERSION_1_1
        subprojectB.javaSourceSettings.targetBytecodeVersion == JavaVersion.VERSION_1_2
        subprojectC.javaSourceSettings.targetBytecodeVersion == JavaVersion.VERSION_1_3
    }

        IdeaLanguageLevel languageLevel = resolveRootLanguageLevel(ideaProjectExt, allIsolatedIdeaModules);
        JavaVersion targetBytecodeVersion = resolveRootTargetBytecodeVersion(ideaProjectExt, allIsolatedIdeaModules);

        DefaultIdeaProject out = buildWithoutChildren(ideaProjectExt, languageLevel, targetBytecodeVersion);

        // Important to build GradleProject after the IsolatedIdeaModuleInternal requests,

import java.io.Serializable;

public class DefaultEclipseJavaSourceSettings implements Serializable {
    private JavaVersion sourceLanguageLevel;
    private JavaVersion targetBytecodeVersion;
    private DefaultInstalledJdk jdk;

    public DefaultEclipseJavaSourceSettings setSourceLanguageLevel(JavaVersion sourceLanguageLevel) {
        this.sourceLanguageLevel = sourceLanguageLevel;
        return this;

        originalIdeaModel.javaLanguageSettings.targetBytecodeVersion == JavaVersion.VERSION_1_8
        originalIdeaModel.modules.name == ["root", "lib1", "lib2"]
        originalIdeaModel.modules[1].javaLanguageSettings.languageLevel == JavaVersion.VERSION_1_7
        originalIdeaModel.modules[1].javaLanguageSettings.targetBytecodeVersion == JavaVersion.VERSION_1_7

     */
    public JavaVersion getTargetBytecodeVersion() {
        return targetBytecodeVersion;
    }

    public void setTargetBytecodeVersion(JavaVersion targetBytecodeVersion) {
        this.targetBytecodeVersion = targetBytecodeVersion;
    }

    /**
     * The vcs for the project.
     * <p>

                javaSourceSettings?.jdk?.javaHome
                withJava(javaSourceSettings?.jdk?.javaVersion)
                withJava(javaSourceSettings?.sourceLanguageLevel)
                withJava(javaSourceSettings?.targetBytecodeVersion)
                projectNatures.each {
                    it.id
                }
                projectDependencies.each {
                    it.exported
                    it.path
                }

        when:
        def ideaProject = loadIdeaProjectModel()

        then:
        ideaProject.javaLanguageSettings.languageLevel == JavaVersion.VERSION_1_8
        ideaProject.javaLanguageSettings.targetBytecodeVersion == JavaVersion.VERSION_1_8
    }

    private IdeaProject loadIdeaProjectModel() {
        withConnection { connection -> connection.getModel(IdeaProject) }
    }