IntelliJ has a code inspection feature that is designed to prevent null pointer exceptions based on static code analysis - actually a kind of interesting idea, and the folks over at IntelliJ have recommended that the annotations be included in the Java SDK in the future. I noticed this feature when I was cleaning up some code today and found a cryptic error message in the IntelliJ code inspection tool: Not annotated method overrides method annotated with @NotNull The community documentation for IntelliJ has a nice explanation of this feature , and there is a Maven repository available. The dependency for version 12 of IntelliJ is the following: <!-- STATIC CODE INSPECTIONS --> <dependency> <groupId>com.intellij</groupId> <artifactId>annotations</artifactId> <version>12.0</version> </dependency> Adding the @NotNull annotation to my overridden method and to a parameter seems to have cleared up the issue. I'm