@Nullable
  private PsiMethod collectExceptions(List<PsiClassType> unhandled) {
    PsiElement targetElement = null;
    PsiMethod targetMethod = null;

    final PsiElement psiElement =
        myWrongElement instanceof PsiMethodReferenceExpression
            ? myWrongElement
            : PsiTreeUtil.getParentOfType(
                myWrongElement, PsiFunctionalExpression.class, PsiMethod.class);
    if (psiElement instanceof PsiFunctionalExpression) {
      targetMethod = LambdaUtil.getFunctionalInterfaceMethod(psiElement);
      targetElement =
          psiElement instanceof PsiLambdaExpression
              ? ((PsiLambdaExpression) psiElement).getBody()
              : psiElement;
    } else if (psiElement instanceof PsiMethod) {
      targetMethod = (PsiMethod) psiElement;
      targetElement = psiElement;
    }

    if (targetElement == null || targetMethod == null || !targetMethod.getThrowsList().isPhysical())
      return null;
    List<PsiClassType> exceptions =
        getUnhandledExceptions(myWrongElement, targetElement, targetMethod);
    if (exceptions == null || exceptions.isEmpty()) return null;
    unhandled.addAll(exceptions);
    return targetMethod;
  }
 @Nullable
 private static PsiMethod getScopeMethod(PsiElement block) {
   PsiElement parent = block.getParent();
   if (parent instanceof PsiMethod) return (PsiMethod) parent;
   if (parent instanceof PsiLambdaExpression)
     return LambdaUtil.getFunctionalInterfaceMethod(
         ((PsiLambdaExpression) parent).getFunctionalInterfaceType());
   return null;
 }
  static PsiSubstitutor infer(
      @NotNull PsiTypeParameter[] typeParameters,
      @NotNull PsiParameter[] parameters,
      @NotNull PsiExpression[] arguments,
      @NotNull PsiSubstitutor partialSubstitutor,
      @NotNull final PsiElement parent,
      @NotNull final ParameterTypeInferencePolicy policy) {
    if (parent instanceof PsiCall) {
      final PsiExpressionList argumentList = ((PsiCall) parent).getArgumentList();
      final MethodCandidateInfo.CurrentCandidateProperties properties =
          MethodCandidateInfo.getCurrentMethod(argumentList);
      // overload resolution can't depend on outer call => should not traverse to top
      if (properties != null
          && !properties.isApplicabilityCheck()
          &&
          // in order to to avoid caching of candidates's errors on parent (!) , so check for
          // overload resolution is left here
          // But overload resolution can depend on type of lambda parameter. As it can't depend on
          // lambda body,
          // traversing down would stop at lambda level and won't take into account overloaded
          // method
          !MethodCandidateInfo.ourOverloadGuard.currentStack().contains(argumentList)) {
        final PsiCall topLevelCall =
            PsiResolveHelper.ourGraphGuard.doPreventingRecursion(
                parent,
                false,
                new Computable<PsiCall>() {
                  @Override
                  public PsiCall compute() {
                    if (parent instanceof PsiExpression
                        && !PsiPolyExpressionUtil.isPolyExpression((PsiExpression) parent)) {
                      return null;
                    }
                    return LambdaUtil.treeWalkUp(parent);
                  }
                });
        if (topLevelCall != null) {

          InferenceSession session;
          if (MethodCandidateInfo.isOverloadCheck()
              || !PsiDiamondType.ourDiamondGuard.currentStack().isEmpty()
              || LambdaUtil.isLambdaParameterCheck()) {
            session = startTopLevelInference(topLevelCall, policy);
          } else {
            session =
                CachedValuesManager.getCachedValue(
                    topLevelCall,
                    new CachedValueProvider<InferenceSession>() {
                      @Nullable
                      @Override
                      public Result<InferenceSession> compute() {
                        return new Result<InferenceSession>(
                            startTopLevelInference(topLevelCall, policy),
                            PsiModificationTracker.MODIFICATION_COUNT);
                      }
                    });

            if (session != null) {
              // reject cached top level session if it was based on wrong candidate: check nested
              // session if candidate (it's type parameters) are the same
              // such situations are avoided when overload resolution is performed
              // (MethodCandidateInfo.isOverloadCheck above)
              // but situations when client code iterates through
              // PsiResolveHelper.getReferencedMethodCandidates or similar are impossible to guess
              final Map<PsiElement, InferenceSession> sessions =
                  session.getInferenceSessionContainer().myNestedSessions;
              final InferenceSession childSession = sessions.get(parent);
              if (childSession != null) {
                for (PsiTypeParameter parameter : typeParameters) {
                  if (!childSession
                      .getInferenceSubstitution()
                      .getSubstitutionMap()
                      .containsKey(parameter)) {
                    session = startTopLevelInference(topLevelCall, policy);
                    break;
                  }
                }
              }
            }
          }

          if (session != null) {
            final PsiSubstitutor childSubstitutor =
                inferNested(
                    typeParameters,
                    parameters,
                    arguments,
                    partialSubstitutor,
                    (PsiCall) parent,
                    policy,
                    properties,
                    session);
            if (childSubstitutor != null) return childSubstitutor;
          } else if (topLevelCall instanceof PsiMethodCallExpression) {
            return new InferenceSession(
                    typeParameters, partialSubstitutor, parent.getManager(), parent, policy)
                .prepareSubstitution();
          }
        }
      }
    }

    final InferenceSession inferenceSession =
        new InferenceSession(
            typeParameters, partialSubstitutor, parent.getManager(), parent, policy);
    inferenceSession.initExpressionConstraints(parameters, arguments, parent);
    return inferenceSession.infer(parameters, arguments, parent);
  }
  private static PsiSubstitutor inferNested(
      final PsiTypeParameter[] typeParameters,
      @NotNull final PsiParameter[] parameters,
      @NotNull final PsiExpression[] arguments,
      final PsiSubstitutor partialSubstitutor,
      @NotNull final PsiCall parent,
      @NotNull final ParameterTypeInferencePolicy policy,
      final MethodCandidateInfo.CurrentCandidateProperties properties,
      final InferenceSession parentSession) {
    final CompoundInitialState compoundInitialState = createState(parentSession);
    InitialInferenceState initialInferenceState = compoundInitialState.getInitialState(parent);
    if (initialInferenceState != null) {
      final InferenceSession childSession = new InferenceSession(initialInferenceState);
      final List<String> errorMessages = parentSession.getIncompatibleErrorMessages();
      if (errorMessages != null) {
        return childSession.prepareSubstitution();
      }
      return childSession.collectAdditionalAndInfer(
          parameters, arguments, properties, compoundInitialState.getInitialSubstitutor());
    }

    // we do not investigate lambda return expressions when lambda's return type is already inferred
    // (proper)
    // this way all calls from lambda's return expressions won't appear in nested sessions
    else {
      PsiElement gParent = PsiUtil.skipParenthesizedExprUp(parent.getParent());
      // find the nearest parent which appears in the map and start inference with a provided target
      // type for a nested lambda
      while (true) {
        if (gParent instanceof PsiReturnStatement) { // process code block lambda
          final PsiElement returnContainer = gParent.getParent();
          if (returnContainer instanceof PsiCodeBlock) {
            gParent = returnContainer.getParent();
          }
        }
        if (gParent instanceof PsiLambdaExpression) {
          final PsiCall call = PsiTreeUtil.getParentOfType(gParent, PsiCall.class);
          if (call != null) {
            initialInferenceState = compoundInitialState.getInitialState(call);
            if (initialInferenceState != null) {
              final int idx = LambdaUtil.getLambdaIdx(call.getArgumentList(), gParent);
              final PsiMethod method = call.resolveMethod();
              if (method != null && idx > -1) {
                final PsiType parameterType =
                    PsiTypesUtil.getParameterType(
                        method.getParameterList().getParameters(), idx, true);
                final PsiType parameterTypeInTermsOfSession =
                    initialInferenceState.getInferenceSubstitutor().substitute(parameterType);
                final PsiType lambdaTargetType =
                    compoundInitialState
                        .getInitialSubstitutor()
                        .substitute(parameterTypeInTermsOfSession);
                return LambdaUtil.performWithLambdaTargetType(
                    (PsiLambdaExpression) gParent,
                    lambdaTargetType,
                    new Producer<PsiSubstitutor>() {
                      @Nullable
                      @Override
                      public PsiSubstitutor produce() {
                        if (call.equals(PsiTreeUtil.getParentOfType(parent, PsiCall.class, true))) {
                          // parent was mentioned in the top inference session
                          // just proceed with the target type
                          final InferenceSession inferenceSession =
                              new InferenceSession(
                                  typeParameters,
                                  partialSubstitutor,
                                  parent.getManager(),
                                  parent,
                                  policy);
                          inferenceSession.initExpressionConstraints(parameters, arguments, parent);
                          return inferenceSession.infer(parameters, arguments, parent);
                        }
                        // one of the grand parents were found in the top inference session
                        // start from it as it is the top level call
                        final InferenceSession sessionInsideLambda =
                            startTopLevelInference(call, policy);
                        return inferNested(
                            typeParameters,
                            parameters,
                            arguments,
                            partialSubstitutor,
                            parent,
                            policy,
                            properties,
                            sessionInsideLambda);
                      }
                    });
              }
            } else {
              gParent = PsiUtil.skipParenthesizedExprUp(call.getParent());
              continue;
            }
          }
        }
        break;
      }
    }
    return null;
  }