@Override
  public String handleEmptyLookup(
      @NotNull final CompletionParameters parameters, final Editor editor) {
    if (!(parameters.getOriginalFile() instanceof PsiJavaFile)) return null;

    final String ad = advertise(parameters);
    final String suffix = ad == null ? "" : "; " + StringUtil.decapitalize(ad);
    if (parameters.getCompletionType() == CompletionType.SMART) {
      if (!ApplicationManager.getApplication().isUnitTestMode()) {

        final Project project = parameters.getPosition().getProject();
        final PsiFile file = parameters.getOriginalFile();

        PsiExpression expression =
            PsiTreeUtil.getContextOfType(parameters.getPosition(), PsiExpression.class, true);
        if (expression != null && expression.getParent() instanceof PsiExpressionList) {
          int lbraceOffset = expression.getParent().getTextRange().getStartOffset();
          ShowParameterInfoHandler.invoke(project, editor, file, lbraceOffset, null);
        }

        if (expression instanceof PsiLiteralExpression) {
          return LangBundle.message("completion.no.suggestions") + suffix;
        }

        if (expression instanceof PsiInstanceOfExpression) {
          final PsiInstanceOfExpression instanceOfExpression = (PsiInstanceOfExpression) expression;
          if (PsiTreeUtil.isAncestor(
              instanceOfExpression.getCheckType(), parameters.getPosition(), false)) {
            return LangBundle.message("completion.no.suggestions") + suffix;
          }
        }
      }

      final Set<PsiType> expectedTypes = JavaCompletionUtil.getExpectedTypes(parameters);
      if (expectedTypes != null) {
        PsiType type = expectedTypes.size() == 1 ? expectedTypes.iterator().next() : null;
        if (type != null) {
          final PsiType deepComponentType = type.getDeepComponentType();
          if (deepComponentType instanceof PsiClassType) {
            if (((PsiClassType) deepComponentType).resolve() != null) {
              return CompletionBundle.message(
                      "completion.no.suggestions.of.type", type.getPresentableText())
                  + suffix;
            }
            return CompletionBundle.message("completion.unknown.type", type.getPresentableText())
                + suffix;
          }
          if (!PsiType.NULL.equals(type)) {
            return CompletionBundle.message(
                    "completion.no.suggestions.of.type", type.getPresentableText())
                + suffix;
          }
        }
      }
    }
    return LangBundle.message("completion.no.suggestions") + suffix;
  }
  private static void addKeywords(CompletionParameters parameters, CompletionResultSet result) {
    PsiElement position = parameters.getPosition();
    final Set<LookupElement> lookupSet = new LinkedHashSet<LookupElement>();
    final Set<CompletionVariant> keywordVariants = new HashSet<CompletionVariant>();
    final JavaCompletionData completionData = getCompletionData(PsiUtil.getLanguageLevel(position));
    completionData.addKeywordVariants(keywordVariants, position, parameters.getOriginalFile());
    completionData.completeKeywordsBySet(
        lookupSet,
        keywordVariants,
        position,
        result.getPrefixMatcher(),
        parameters.getOriginalFile());
    completionData.fillCompletions(parameters, result);

    for (final LookupElement item : lookupSet) {
      result.addElement(item);
    }
  }
  @Override
  public String advertise(@NotNull final CompletionParameters parameters) {
    if (!(parameters.getOriginalFile() instanceof PsiJavaFile)) return null;

    if (parameters.getCompletionType() == CompletionType.BASIC
        && parameters.getInvocationCount() > 0) {
      PsiElement position = parameters.getPosition();
      if (psiElement()
          .withParent(
              psiReferenceExpression()
                  .withFirstChild(psiReferenceExpression().referencing(psiClass())))
          .accepts(position)) {
        if (CompletionUtil.shouldShowFeature(
            parameters, JavaCompletionFeatures.GLOBAL_MEMBER_NAME)) {
          final String shortcut = getActionShortcut(IdeActions.ACTION_CODE_COMPLETION);
          if (shortcut != null) {
            return "Pressing "
                + shortcut
                + " twice without a class qualifier would show all accessible static methods";
          }
        }
      }
    }

    if (parameters.getCompletionType() != CompletionType.SMART
        && shouldSuggestSmartCompletion(parameters.getPosition())) {
      if (CompletionUtil.shouldShowFeature(
          parameters, CodeCompletionFeatures.EDITING_COMPLETION_SMARTTYPE_GENERAL)) {
        final String shortcut = getActionShortcut(IdeActions.ACTION_SMART_TYPE_COMPLETION);
        if (shortcut != null) {
          return CompletionBundle.message("completion.smart.hint", shortcut);
        }
      }
    }

    if (parameters.getCompletionType() == CompletionType.SMART
        && parameters.getInvocationCount() == 1) {
      final PsiType[] psiTypes =
          ExpectedTypesGetter.getExpectedTypes(parameters.getPosition(), true);
      if (psiTypes.length > 0) {
        if (CompletionUtil.shouldShowFeature(
            parameters, JavaCompletionFeatures.SECOND_SMART_COMPLETION_TOAR)) {
          final String shortcut = getActionShortcut(IdeActions.ACTION_SMART_TYPE_COMPLETION);
          if (shortcut != null) {
            for (final PsiType psiType : psiTypes) {
              final PsiType type = PsiUtil.extractIterableTypeParameter(psiType, false);
              if (type != null) {
                return CompletionBundle.message(
                    "completion.smart.aslist.hint", shortcut, type.getPresentableText());
              }
            }
          }
        }
        if (CompletionUtil.shouldShowFeature(
            parameters, JavaCompletionFeatures.SECOND_SMART_COMPLETION_ASLIST)) {
          final String shortcut = getActionShortcut(IdeActions.ACTION_SMART_TYPE_COMPLETION);
          if (shortcut != null) {
            for (final PsiType psiType : psiTypes) {
              if (psiType instanceof PsiArrayType) {
                final PsiType componentType = ((PsiArrayType) psiType).getComponentType();
                if (!(componentType instanceof PsiPrimitiveType)) {
                  return CompletionBundle.message(
                      "completion.smart.toar.hint", shortcut, componentType.getPresentableText());
                }
              }
            }
          }
        }

        if (CompletionUtil.shouldShowFeature(
            parameters, JavaCompletionFeatures.SECOND_SMART_COMPLETION_CHAIN)) {
          final String shortcut = getActionShortcut(IdeActions.ACTION_SMART_TYPE_COMPLETION);
          if (shortcut != null) {
            return CompletionBundle.message("completion.smart.chain.hint", shortcut);
          }
        }
      }
    }
    return null;
  }