How to use

ProjectFileIndex$SERVICE

in

com.intellij.openapi.roots

@Nullable
public static Sdk mostSpecificSdk(@NotNull PsiElement psiElement) {
  Project project = psiElement.getProject();
  Sdk elixirSdk;
  /* ModuleUtilCore.findModuleForPsiElement can fail with NullPointerException if the
    ProjectFileIndex.SERVICE.getInstance(Project) returns {@code null}, so check that the ProjectFileIndex is
    available first */
  if (ProjectFileIndex.SERVICE.getInstance(project) != null) {
    Module module = ModuleUtilCore.findModuleForPsiElement(psiElement);
    if (module != null) {
      elixirSdk = mostSpecificSdk(module);
    } else {
      elixirSdk = mostSpecificSdk(project);
    }
  } else {
    elixirSdk = mostSpecificSdk(project);
  }
  return elixirSdk;
}

boolean hasPackage = StringUtil.isNotEmpty(targetPackage);
ProjectRootManager rootManager = ProjectRootManager.getInstance(project);
ProjectFileIndex fileIndex = ProjectFileIndex.SERVICE.getInstance(project);

@Override
public void apply(
 @NotNull final PsiFile file,
 final AnnotationResult annotationResult,
 @NotNull final AnnotationHolder holder
) {
 if (
  null == file.getVirtualFile() ||
   null == ProjectFileIndex.SERVICE.getInstance(file.getProject()).getContentRootForFile(file.getVirtualFile()) ||
   (
    // Fixes #106: Annotations in PHPStorm shown twice per File
    "html".equalsIgnoreCase(file.getFileType().getName()) &&
     "php".equalsIgnoreCase(file.getVirtualFile().getExtension()))
  ) {
  return;
 }
 createAnnotations(file,annotationResult,holder);
}

@CheckForNull
public Module findModuleForFile(VirtualFile file, Project project) {
 ApplicationManager.getApplication().assertReadAccessAllowed();
 return ProjectFileIndex.SERVICE.getInstance(project).getModuleForFile(file, false);
}

final ProjectFileIndex projectFileIndex = ProjectFileIndex.SERVICE.getInstance(project);
if (projectFileIndex != null) {
  if (!projectFileIndex.isInSourceContent(selectedFile)) {

private static boolean isInSource(@NotNull final PsiFile psiFile, final PluginConfigurationManager pluginConfig) {
  return pluginConfig.getCurrent().getScanScope() == ScanScope.Everything
    || ProjectFileIndex.SERVICE.getInstance(psiFile.getProject()).isInSourceContent(psiFile.getVirtualFile());
}