@Nullable
 private Sdk getSdk() {
   if (myModule == null) {
     return ProjectRootManager.getInstance(myProject).getProjectSdk();
   }
   final ModuleRootManager rootManager = ModuleRootManager.getInstance(myModule);
   return rootManager.getSdk();
 }
 @TestOnly
 public static void setTestVersion(
     @NotNull final JavaSdkVersion testVersion,
     @NotNull Module module,
     @NotNull Disposable parentDisposable) {
   ModuleRootManager rootManager = ModuleRootManager.getInstance(module);
   final Sdk sdk = rootManager.getSdk();
   final String oldVersionString = sdk.getVersionString();
   ((ProjectJdkImpl) sdk).setVersionString(testVersion.getDescription());
   assert JavaSdk.getInstance().getVersion(sdk) == testVersion;
   Disposer.register(
       parentDisposable,
       new Disposable() {
         @Override
         public void dispose() {
           ((ProjectJdkImpl) sdk).setVersionString(oldVersionString);
         }
       });
 }