@Override
      public void visitMethodReferenceExpression(@NotNull PsiMethodReferenceExpression expression) {
        super.visitMethodReferenceExpression(expression);
        if (!REPORT_UNSOUND_WARNINGS) return;
        final PsiElement resolve = expression.resolve();
        if (resolve instanceof PsiMethod) {
          final PsiType methodReturnType = ((PsiMethod)resolve).getReturnType();
          if (TypeConversionUtil.isPrimitiveWrapper(methodReturnType) && NullableNotNullManager.isNullable((PsiMethod)resolve)) {
            final PsiType returnType = LambdaUtil.getFunctionalInterfaceReturnType(expression);
            if (TypeConversionUtil.isPrimitiveAndNotNull(returnType)) {
              holder.registerProblem(expression, JavaAnalysisBundle.message("dataflow.message.unboxing.method.reference"));
            }
          }
        }
      }
@Override
      public void visitMethodReferenceExpression(@NotNull PsiMethodReferenceExpression expression)