diff --git a/python/psi-api/src/com/jetbrains/python/psi/stubs/PyClassStub.java b/python/psi-api/src/com/jetbrains/python/psi/stubs/PyClassStub.java
index db296355b2fa..88b677cc2d69 100644
--- a/python/psi-api/src/com/jetbrains/python/psi/stubs/PyClassStub.java
+++ b/python/psi-api/src/com/jetbrains/python/psi/stubs/PyClassStub.java
@@ -44,7 +44,6 @@ public interface PyClassStub extends NamedStub<PyClass> {
   @NotNull
   List<String> getSubscriptedSuperClasses();
 
-
   @Nullable
   QualifiedName getMetaClass();
 
diff --git a/python/src/com/jetbrains/python/psi/PyFileElementType.java b/python/src/com/jetbrains/python/psi/PyFileElementType.java
index a6c77063fe7e..d613faa3d1df 100644
--- a/python/src/com/jetbrains/python/psi/PyFileElementType.java
+++ b/python/src/com/jetbrains/python/psi/PyFileElementType.java
@@ -62,7 +62,7 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
   @Override
   public int getStubVersion() {
     // Don't forget to update versions of indexes that use the updated stub-based elements
-    return 66;
+    return 67;
   }
 
   @Nullable
diff --git a/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java b/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
index 5cbd1bc55966..9bcdd62df416 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
@@ -343,7 +343,7 @@ public class PyClassImpl extends PyBaseElementImpl<PyClassStub> implements PyCla
         PyPsiUtils.assertValid(PyClassImpl.this);
         final StringBuilder result = new StringBuilder(notNullize(getName(), PyNames.UNNAMED_ELEMENT));
         final List<String> superClassesText = getSuperClassesText();
-        if (superClassesText.size() > 0) {
+        if (!superClassesText.isEmpty()) {
           result.append("(");
           result.append(join(superClassesText, expr -> notNullize(expr, PyNames.UNNAMED_ELEMENT), ", "));
           result.append(")");
@@ -355,8 +355,8 @@ public class PyClassImpl extends PyBaseElementImpl<PyClassStub> implements PyCla
 
   private List<String> getSuperClassesText() {
     PyClassStub stub = getGreenStub();
-    if (stub == null || stub.getSuperClassesText() == null) {
-      return ContainerUtil.map(getSuperClassExpressions(), exp -> exp.getText());
+    if (stub == null) {
+      return ContainerUtil.map(getSuperClassExpressions(), PsiElement::getText);
     }
     else {
       return stub.getSuperClassesText();
diff --git a/python/src/com/jetbrains/python/psi/impl/stubs/PyClassElementType.java b/python/src/com/jetbrains/python/psi/impl/stubs/PyClassElementType.java
index fe56c2aad168..48dcd73167bd 100644
--- a/python/src/com/jetbrains/python/psi/impl/stubs/PyClassElementType.java
+++ b/python/src/com/jetbrains/python/psi/impl/stubs/PyClassElementType.java
@@ -109,7 +109,6 @@ public class PyClassElementType extends PyStubElementType<PyClassStub, PyClass>
                                             PySubscriptionExpression.class));
   }
 
-
   @Nullable
   private static QualifiedName resolveOriginalSuperClassQName(@NotNull PyExpression superClassExpression) {
     if (superClassExpression instanceof PyReferenceExpression) {
@@ -148,7 +147,6 @@ public class PyClassElementType extends PyStubElementType<PyClassStub, PyClass>
 
     final List<String> subscriptedBaseClassesText = pyClassStub.getSubscriptedSuperClasses();
     final List<String> baseClassesText = pyClassStub.getSuperClassesText();
-    assert baseClassesText != null;
 
     dataStream.writeByte(baseClassesText.size());
     for (String text : baseClassesText) {
diff --git a/python/src/com/jetbrains/python/psi/impl/stubs/PyClassStubImpl.java b/python/src/com/jetbrains/python/psi/impl/stubs/PyClassStubImpl.java
index 6b1f0be2d5cd..bc8c4fd7abd9 100644
--- a/python/src/com/jetbrains/python/psi/impl/stubs/PyClassStubImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/stubs/PyClassStubImpl.java
@@ -24,14 +24,14 @@ import com.jetbrains.python.psi.stubs.PyClassStub;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
 /**
  * @author max
  */
-public class
-PyClassStubImpl extends StubBase<PyClass> implements PyClassStub {
+public class PyClassStubImpl extends StubBase<PyClass> implements PyClassStub {
 
   @Nullable
   private final String myName;
@@ -49,7 +49,7 @@ PyClassStubImpl extends StubBase<PyClass> implements PyClassStub {
   @Nullable
   private final String myDocString;
 
-  @Nullable
+  @NotNull
   private final List<String> mySuperClassesText;
 
   public PyClassStubImpl(@Nullable String name,
@@ -60,14 +60,14 @@ PyClassStubImpl extends StubBase<PyClass> implements PyClassStub {
                          @Nullable List<String> slots,
                          @Nullable String docString,
                          @NotNull IStubElementType stubElementType) {
-    this(name, parentStub, superClasses, subscriptedSuperClassesText, null, metaClass, slots, docString, stubElementType);
+    this(name, parentStub, superClasses, subscriptedSuperClassesText, Collections.emptyList(), metaClass, slots, docString, stubElementType);
   }
 
   public PyClassStubImpl(@Nullable String name,
                          @Nullable StubElement parentStub,
                          @NotNull Map<QualifiedName, QualifiedName> superClasses,
                          @NotNull List<String> subscriptedSuperClassesText,
-                         @Nullable List<String> superClassesText,
+                         @NotNull List<String> superClassesText,
                          @Nullable QualifiedName metaClass,
                          @Nullable List<String> slots,
                          @Nullable String docString,