private static void checkMethodCall(RefElement refWhat, final PsiElement element) {
    if (!(refWhat instanceof RefMethod)) return;
    final RefMethod refMethod = (RefMethod) refWhat;
    final PsiElement psiElement = refMethod.getElement();
    if (!(psiElement instanceof PsiMethod)) return;
    final PsiMethod psiMethod = (PsiMethod) psiElement;
    if (!PsiType.BOOLEAN.equals(psiMethod.getReturnType())) return;
    element.accept(
        new JavaRecursiveElementWalkingVisitor() {
          @Override
          public void visitMethodCallExpression(PsiMethodCallExpression call) {
            super.visitMethodCallExpression(call);
            final PsiReferenceExpression methodExpression = call.getMethodExpression();
            if (methodExpression.isReferenceTo(psiMethod)) {
              if (isInvertedMethodCall(methodExpression)) return;
              refMethod.putUserData(ALWAYS_INVERTED, Boolean.FALSE);
            }
          }

          @Override
          public void visitMethodReferenceExpression(PsiMethodReferenceExpression expression) {
            super.visitMethodReferenceExpression(expression);
            if (expression.isReferenceTo(psiElement)) {
              refMethod.putUserData(ALWAYS_INVERTED, Boolean.FALSE);
            }
          }
        });
  }
  @Override
  public CommonProblemDescriptor[] checkElement(
      @NotNull RefEntity refEntity,
      @NotNull AnalysisScope scope,
      @NotNull final InspectionManager manager,
      @NotNull final GlobalInspectionContext globalContext) {
    if (refEntity instanceof RefMethod) {
      RefMethod refMethod = (RefMethod) refEntity;
      if (!refMethod.isReferenced()) return null;
      if (hasNonInvertedCalls(refMethod)) return null;
      if (!refMethod.getSuperMethods().isEmpty()) return null;
      final PsiMethod psiMethod = (PsiMethod) refMethod.getElement();
      final PsiIdentifier psiIdentifier = psiMethod.getNameIdentifier();
      if (psiIdentifier != null) {
        final Collection<RefElement> inReferences = refMethod.getInReferences();
        if (inReferences.size() == 1) {
          final RefElement refElement = inReferences.iterator().next();
          final PsiElement usagesContainer = refElement.getElement();
          if (usagesContainer == null) return null;
          if (ReferencesSearch.search(psiMethod, new LocalSearchScope(usagesContainer))
              .forEach(
                  new Processor<PsiReference>() {
                    private final Set<PsiReference> myFoundRefs = new HashSet<>();

                    @Override
                    public boolean process(PsiReference reference) {
                      myFoundRefs.add(reference);
                      return myFoundRefs.size() < 2;
                    }
                  })) return null;
        }
        return new ProblemDescriptor[] {
          manager.createProblemDescriptor(
              psiIdentifier,
              InspectionsBundle.message("boolean.method.is.always.inverted.problem.descriptor"),
              (LocalQuickFix) getQuickFix(null),
              ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
              false)
        };
      }
    }
    return null;
  }