From 36862ed0055a805d1d969a1eb9add9cc959bbea0 Mon Sep 17 00:00:00 2001
From: Alexey Kudravtsev <cdr@intellij.com>
Date: Mon, 13 Aug 2018 17:24:57 +0300
Subject: [PATCH] fix NPE

---
 .../src/com/siyeh/ig/style/BoundedWildcardInspection.java  | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/plugins/InspectionGadgets/src/com/siyeh/ig/style/BoundedWildcardInspection.java b/plugins/InspectionGadgets/src/com/siyeh/ig/style/BoundedWildcardInspection.java
index b861a761fc6d..8d9c8965e558 100644
--- a/plugins/InspectionGadgets/src/com/siyeh/ig/style/BoundedWildcardInspection.java
+++ b/plugins/InspectionGadgets/src/com/siyeh/ig/style/BoundedWildcardInspection.java
@@ -31,6 +31,7 @@ import com.intellij.refactoring.changeSignature.JavaChangeSignatureDialog;
 import com.intellij.refactoring.changeSignature.ParameterInfoImpl;
 import com.intellij.ui.components.JBCheckBox;
 import com.intellij.util.ArrayUtil;
+import com.intellij.util.ObjectUtils;
 import com.intellij.util.containers.ContainerUtil;
 import com.siyeh.InspectionGadgetsBundle;
 import org.jdom.Element;
@@ -268,8 +269,10 @@ public class BoundedWildcardInspection extends AbstractBaseJavaLocalInspectionTo
         PsiField fieldCopy = classCopy.getFields()[fieldIndex];
         Collection<PsiReference> refs = ReferencesSearch.search(fieldCopy, new LocalSearchScope(classCopy)).findAll();
         Map<PsiMethod, List<PsiReference>> collect =
-          refs.stream().collect(Collectors.groupingBy(ref -> PsiTreeUtil.getParentOfType(ref.getElement(), PsiMethod.class)));
-        methodsToErrorCheck = collect.keySet();
+          refs.stream()
+            // map null to "method" to filter it out later
+            .collect(Collectors.groupingBy(ref -> ObjectUtils.notNull(PsiTreeUtil.getParentOfType(ref.getElement(), PsiMethod.class), method)));
+        methodsToErrorCheck = ContainerUtil.filter(collect.keySet(), k->k != method);
       }
       else {
         methodsToErrorCheck = Collections.singletonList(methodCopyInClass);