Checker Framework argument.type.incompatible undesired positive

Question

So I'm getting this error from the nullness checker

> Task :compileJava
/Users/calebcushing/IdeaProjects/ppm/scaf/src/main/java/com/xenoterracide/scaf/PebbleTemplateProcessor.java:94: error: [argument.type.incompatible] incompatible argument for parameter obj of requireNonNull.
        var console = Objects.requireNonNull( System.console() );
                                                            ^                                     ^

this is complaining that System.console() could be null, which upon reading the javadoc is true. So I wrapped it in Objects.requireNonNull() now it's complaining that the argument to requireNonNull can't be null, which is obviously not true.

How do I tell NullnessChecker to ignore Objects.requireNonNull()? I'm fine with NPE's that are explicit, it's just the accidental ones I don't want. I believe checker already ships with a stub for this.

Answer 1

Realize I'm late to the game, but hopefully this will help others who land here after searching.

You can provide a stub file to Checker which overrides the default annotations.

For my own project, I created a new folder called checker alongside the src folder in one of my common projects, and dropped in a stub file java.util.Objects.astub with these contents:

package java.util;

import org.eclipse.jdt.annotation.Nullable;

public class Objects
{
   public static <T> T requireNonNull(@Nullable T obj, String message);
}

Then I added this to our Gradle build:

checkerFramework {
   extraJavacArgs = [
      "-Astubs=${project(':my-project').file('checker')}"
   ]
}

…where my-project is the Gradle identifier for the project containing the new folder.

Checker will now load all *.astub files in that checker folder, and use the annotations provided there instead of the defaults. You can learn more at Using Stub Classes in the Checker documentation.