Block rxjava3 nullable/nonnull imports in checkstyle

checkstyle/checkstyle.xml

@@ -96,7 +96,13 @@
         <!-- See https://checkstyle.org/config_import.html -->
         <module name="AvoidStarImport"/>
         <module name="IllegalImport"> <!-- defaults to sun.* packages -->
-            <property name="illegalClasses" value="org.jetbrains.annotations.Nullable, org.jetbrains.annotations.NotNull, javax.annotation.Nullable, javax.annotation.Nonnull" />
+            <property name="illegalClasses" value="
+                org.jetbrains.annotations.Nullable,
+                org.jetbrains.annotations.NotNull,
+                javax.annotation.Nullable,
+                javax.annotation.Nonnull,
+                io.reactivex.rxjava3.annotations.NonNull,
+                io.reactivex.rxjava3.annotations.Nullable" />
         </module>
         <module name="RedundantImport"/>
         <module name="UnusedImports"/>