IDEA-231428 Extract variable after old instanceof could introduce a pattern variable

GitOrigin-RevId: f4ada449f5345bd442949611e736a3cf75c55480

java/java-psi-api/src/com/intellij/psi/PsiPatternVariable.java

@@ -20,6 +20,6 @@ public interface PsiPatternVariable extends PsiParameter {
   @Override
   PsiIdentifier getNameIdentifier();
 
-  @Nullable
+  @NotNull
   PsiPattern getPattern();
 }