public static Set<PsiType> flatten(PsiType[] conjuncts, Set<PsiType> types) {
    for (PsiType conjunct : conjuncts) {
      if (conjunct instanceof PsiIntersectionType) {
        PsiIntersectionType type = (PsiIntersectionType) conjunct;
        flatten(type.getConjuncts(), types);
      } else {
        types.add(conjunct);
      }
    }
    if (types.size() > 1) {
      PsiType[] array = types.toArray(createArray(types.size()));
      for (Iterator<PsiType> iterator = types.iterator(); iterator.hasNext(); ) {
        PsiType type = iterator.next();

        for (PsiType existing : array) {
          if (type != existing) {
            final boolean allowUncheckedConversion =
                type instanceof PsiClassType && ((PsiClassType) type).isRaw();
            if (TypeConversionUtil.isAssignable(type, existing, allowUncheckedConversion)) {
              iterator.remove();
              break;
            }
          }
        }
      }
      if (types.isEmpty()) {
        types.add(array[0]);
      }
    }
    return types;
  }
  public static Set<LookupElement> processJavaReference(
      PsiElement element,
      PsiJavaReference javaReference,
      ElementFilter elementFilter,
      JavaCompletionProcessor.Options options,
      final PrefixMatcher matcher,
      CompletionParameters parameters) {
    final Set<LookupElement> set = new LinkedHashSet<LookupElement>();
    final Condition<String> nameCondition =
        new Condition<String>() {
          @Override
          public boolean value(String s) {
            return matcher.prefixMatches(s);
          }
        };

    PsiMethodCallExpression call =
        PsiTreeUtil.getParentOfType(element, PsiMethodCallExpression.class);
    boolean checkInitialized =
        parameters.getInvocationCount() <= 1
            && call != null
            && PsiKeyword.SUPER.equals(call.getMethodExpression().getText());

    final JavaCompletionProcessor processor =
        new JavaCompletionProcessor(
            element, elementFilter, options.withInitialized(checkInitialized), nameCondition);
    final PsiType plainQualifier = processor.getQualifierType();
    PsiType qualifierType = plainQualifier;

    PsiType runtimeQualifier = getQualifierCastType(javaReference, parameters);
    if (runtimeQualifier != null) {
      PsiType composite =
          qualifierType == null
              ? runtimeQualifier
              : PsiIntersectionType.createIntersection(qualifierType, runtimeQualifier);
      PsiElement ctx = createContextWithXxxVariable(element, composite);
      javaReference =
          (PsiReferenceExpression)
              JavaPsiFacade.getElementFactory(element.getProject())
                  .createExpressionFromText("xxx.xxx", ctx);
      qualifierType = runtimeQualifier;
      processor.setQualifierType(qualifierType);
    }

    javaReference.processVariants(processor);

    final PsiTypeLookupItem castItem =
        runtimeQualifier == null
            ? null
            : PsiTypeLookupItem.createLookupItem(
                runtimeQualifier, (PsiReferenceExpression) javaReference);

    final boolean pkgContext = inSomePackage(element);

    final Set<PsiMember> mentioned = new THashSet<PsiMember>();
    for (CompletionElement completionElement : processor.getResults()) {
      for (LookupElement item : createLookupElements(completionElement, javaReference)) {
        item.putUserData(QUALIFIER_TYPE_ATTR, qualifierType);
        final Object o = item.getObject();
        if (o instanceof PsiClass && !isSourceLevelAccessible(element, (PsiClass) o, pkgContext)) {
          continue;
        }
        if (o instanceof PsiMember) {
          if (isInExcludedPackage((PsiMember) o, true)) {
            continue;
          }
          mentioned.add(CompletionUtil.getOriginalOrSelf((PsiMember) o));
        }
        set.add(
            highlightIfNeeded(
                qualifierType,
                castQualifier(item, castItem, plainQualifier, processor),
                o,
                element));
      }
    }

    if (javaReference instanceof PsiJavaCodeReferenceElement
        && !((PsiJavaCodeReferenceElement) javaReference).isQualified()) {
      final StaticMemberProcessor memberProcessor = new JavaStaticMemberProcessor(parameters);
      memberProcessor.processMembersOfRegisteredClasses(
          matcher,
          new PairConsumer<PsiMember, PsiClass>() {
            @Override
            public void consume(PsiMember member, PsiClass psiClass) {
              if (!mentioned.contains(member)
                  && processor.satisfies(member, ResolveState.initial())) {
                set.add(memberProcessor.createLookupElement(member, psiClass, true));
              }
            }
          });
    }

    return set;
  }
  @NotNull
  private static PsiType getLeastUpperBound(
      PsiType type1, PsiType type2, Set<Pair<PsiType, PsiType>> compared, PsiManager manager) {
    if (type1 instanceof PsiCapturedWildcardType) {
      return getLeastUpperBound(
          ((PsiCapturedWildcardType) type1).getUpperBound(), type2, compared, manager);
    }
    if (type2 instanceof PsiCapturedWildcardType) {
      return getLeastUpperBound(
          type1, ((PsiCapturedWildcardType) type2).getUpperBound(), compared, manager);
    }

    if (type1 instanceof PsiWildcardType) {
      return getLeastUpperBound(
          ((PsiWildcardType) type1).getExtendsBound(), type2, compared, manager);
    }
    if (type2 instanceof PsiWildcardType) {
      return getLeastUpperBound(
          type1, ((PsiWildcardType) type2).getExtendsBound(), compared, manager);
    }

    if (type1 instanceof PsiArrayType && type2 instanceof PsiArrayType) {
      final PsiType componentType1 = ((PsiArrayType) type1).getComponentType();
      final PsiType componentType2 = ((PsiArrayType) type2).getComponentType();
      final PsiType componentType =
          getLeastUpperBound(componentType1, componentType2, compared, manager);
      if (componentType1 instanceof PsiPrimitiveType
          && componentType2 instanceof PsiPrimitiveType
          && componentType.equalsToText(CommonClassNames.JAVA_LANG_OBJECT)) {
        final PsiElementFactory factory =
            JavaPsiFacade.getInstance(manager.getProject()).getElementFactory();
        final GlobalSearchScope resolveScope = GlobalSearchScope.allScope(manager.getProject());
        final PsiClassType cloneable =
            factory.createTypeByFQClassName(CommonClassNames.JAVA_LANG_CLONEABLE, resolveScope);
        final PsiClassType serializable =
            factory.createTypeByFQClassName(CommonClassNames.JAVA_IO_SERIALIZABLE, resolveScope);
        return PsiIntersectionType.createIntersection(componentType, cloneable, serializable);
      }
      return componentType.createArrayType();
    }
    if (type1 instanceof PsiIntersectionType) {
      Set<PsiType> newConjuncts = new LinkedHashSet<PsiType>();
      final PsiType[] conjuncts = ((PsiIntersectionType) type1).getConjuncts();
      for (PsiType type : conjuncts) {
        newConjuncts.add(getLeastUpperBound(type, type2, compared, manager));
      }
      return PsiIntersectionType.createIntersection(
          newConjuncts.toArray(PsiType.createArray(newConjuncts.size())));
    }
    if (type2 instanceof PsiIntersectionType) {
      return getLeastUpperBound(type2, type1, compared, manager);
    }
    if (type1 instanceof PsiClassType && type2 instanceof PsiClassType) {
      PsiClassType.ClassResolveResult classResolveResult1 =
          ((PsiClassType) type1).resolveGenerics();
      PsiClassType.ClassResolveResult classResolveResult2 =
          ((PsiClassType) type2).resolveGenerics();
      PsiClass aClass = classResolveResult1.getElement();
      PsiClass bClass = classResolveResult2.getElement();
      if (aClass == null || bClass == null) {
        return PsiType.getJavaLangObject(manager, GlobalSearchScope.allScope(manager.getProject()));
      }

      PsiClass[] supers = getLeastUpperClasses(aClass, bClass);
      if (supers.length == 0) {
        return PsiType.getJavaLangObject(manager, aClass.getResolveScope());
      }

      PsiClassType[] conjuncts = new PsiClassType[supers.length];
      for (int i = 0; i < supers.length; i++) {
        PsiClass aSuper = supers[i];
        PsiSubstitutor subst1 =
            TypeConversionUtil.getSuperClassSubstitutor(
                aSuper, aClass, classResolveResult1.getSubstitutor());
        PsiSubstitutor subst2 =
            TypeConversionUtil.getSuperClassSubstitutor(
                aSuper, bClass, classResolveResult2.getSubstitutor());
        PsiSubstitutor substitutor = PsiSubstitutor.EMPTY;
        for (PsiTypeParameter parameter : PsiUtil.typeParametersIterable(aSuper)) {
          PsiType mapping1 = subst1.substitute(parameter);
          PsiType mapping2 = subst2.substitute(parameter);

          if (mapping1 != null && mapping2 != null) {
            substitutor =
                substitutor.put(
                    parameter,
                    getLeastContainingTypeArgument(
                        mapping1,
                        mapping2,
                        compared,
                        manager,
                        type1.equals(mapping1) && type2.equals(mapping2) ? aSuper : null,
                        parameter));
          } else {
            substitutor = substitutor.put(parameter, null);
          }
        }

        conjuncts[i] =
            JavaPsiFacade.getInstance(manager.getProject())
                .getElementFactory()
                .createType(aSuper, substitutor);
      }

      return PsiIntersectionType.createIntersection(conjuncts);
    }
    if (type2 instanceof PsiArrayType && !(type1 instanceof PsiArrayType)) {
      return getLeastUpperBound(type2, type1, compared, manager);
    }
    if (type1 instanceof PsiArrayType) {
      PsiElementFactory factory =
          JavaPsiFacade.getInstance(manager.getProject()).getElementFactory();
      GlobalSearchScope all = GlobalSearchScope.allScope(manager.getProject());
      PsiClassType serializable =
          factory.createTypeByFQClassName(CommonClassNames.JAVA_IO_SERIALIZABLE, all);
      PsiClassType cloneable =
          factory.createTypeByFQClassName(CommonClassNames.JAVA_LANG_CLONEABLE, all);
      PsiType arraySupers = PsiIntersectionType.createIntersection(serializable, cloneable);
      return getLeastUpperBound(arraySupers, type2, compared, manager);
    }

    return PsiType.getJavaLangObject(manager, GlobalSearchScope.allScope(manager.getProject()));
  }
 public static PsiType getGreatestLowerBound(@Nullable PsiType type1, @Nullable PsiType type2) {
   if (type1 == null || type2 == null) return null;
   return PsiIntersectionType.createIntersection(type1, type2);
 }
  @Nullable
  private PsiType getNominalTypeInner(@Nullable PsiElement resolved) {
    if (resolved == null && !"class".equals(getReferenceName())) {
      resolved = resolve();
    }

    if (resolved instanceof PsiClass) {
      final PsiElementFactory factory = JavaPsiFacade.getInstance(getProject()).getElementFactory();
      if (PsiUtil.isInstanceThisRef(this)) {
        final PsiClassType categoryType = GdkMethodUtil.getCategoryType((PsiClass) resolved);
        if (categoryType != null) {
          return categoryType;
        } else {
          return factory.createType((PsiClass) resolved);
        }
      } else if (PsiUtil.isSuperReference(this)) {
        PsiClass contextClass = PsiUtil.getContextClass(this);
        if (GrTraitUtil.isTrait(contextClass)) {
          PsiClassType[] extendsTypes = contextClass.getExtendsListTypes();
          PsiClassType[] implementsTypes = contextClass.getImplementsListTypes();

          PsiClassType[] superTypes =
              ArrayUtil.mergeArrays(implementsTypes, extendsTypes, PsiClassType.ARRAY_FACTORY);

          return PsiIntersectionType.createIntersection(ArrayUtil.reverseArray(superTypes));
        }
        return factory.createType((PsiClass) resolved);
      }
      if (getParent() instanceof GrReferenceExpression) {
        return factory.createType((PsiClass) resolved);
      } else {
        return TypesUtil.createJavaLangClassType(
            factory.createType((PsiClass) resolved), getProject(), getResolveScope());
      }
    }

    if (resolved instanceof GrVariable) {
      return ((GrVariable) resolved).getDeclaredType();
    }

    if (resolved instanceof PsiVariable) {
      return ((PsiVariable) resolved).getType();
    }

    if (resolved instanceof PsiMethod) {
      PsiMethod method = (PsiMethod) resolved;
      if (PropertyUtil.isSimplePropertySetter(method)
          && !method.getName().equals(getReferenceName())) {
        return method.getParameterList().getParameters()[0].getType();
      }

      // 'class' property with explicit generic
      PsiClass containingClass = method.getContainingClass();
      if (containingClass != null
          && CommonClassNames.JAVA_LANG_OBJECT.equals(containingClass.getQualifiedName())
          && "getClass".equals(method.getName())) {
        return TypesUtil.createJavaLangClassType(
            PsiImplUtil.getQualifierType(this), getProject(), getResolveScope());
      }

      return PsiUtil.getSmartReturnType(method);
    }

    if (resolved == null) {
      final PsiType fromClassRef = getTypeFromClassRef(this);
      if (fromClassRef != null) {
        return fromClassRef;
      }

      final PsiType fromMapAccess = getTypeFromMapAccess(this);
      if (fromMapAccess != null) {
        return fromMapAccess;
      }

      final PsiType fromSpreadOperator = getTypeFromSpreadOperator(this);
      if (fromSpreadOperator != null) {
        return fromSpreadOperator;
      }
    }

    return null;
  }