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Add @Nullable to a functional-interface return type argument fed a null-returning lambda

Recipe IDio.moderne.nullability.AddNullableToFunctionalReturnArgumentArtifactio.moderne.recipe:rewrite-nullability

When a null-returning lambda is passed for a functional-interface parameter (such as Function<R, T>) of a method that consumes the produced value in a null-tolerant way, annotates that interface's return type argument @Nullable (Function<R, @Nullable T>) so returning null through the callback is legal under JSpecify/NullAway. This is distinct from widening a pass-through type-parameter bound (handled separately); a de-overlap guard keeps the two from both firing. Only parameters of recognized functional interfaces, on methods declared in the working set, are changed; already-@Nullable and wildcard/raw arguments are left untouched.

Single recipeProprietary

Add to your build

Get a download tokenThis recipe is Moderne licensed, so the token must belong to a Moderne customer. It replaces YOUR_DOWNLOAD_TOKEN below.

~/.gradle/gradle.properties

codeGenomeUsername=you@example.com
codeGenomeToken=YOUR_DOWNLOAD_TOKEN

build.gradle.kts

plugins {
    id("org.openrewrite.rewrite") version("latest.release")
}

rewrite {
    activeRecipe("io.moderne.nullability.AddNullableToFunctionalReturnArgument")
}

repositories {
    mavenCentral()
    maven {
        url = uri("https://artifacts.codegenomeproject.org/maven")
        credentials {
            username = providers.gradleProperty("codeGenomeUsername").get()
            password = providers.gradleProperty("codeGenomeToken").get()
        }
    }
}

dependencies {
    rewrite("io.moderne.recipe:rewrite-nullability:0.6.0")
}

Then run

./gradlew rewriteRun

Usage

This recipe has no required configuration options. You’ll need the Moderne CLI configured before running the command below.

mod run . --recipe io.moderne.nullability.AddNullableToFunctionalReturnArgument

If the recipe isn’t available locally, install it with:

mod config recipes jar install io.moderne.recipe:rewrite-nullability:RELEASE

Data tables

Structured output this recipe can produce.

  • Source files that had resultsSource files that were modified by the recipe run.org.openrewrite.table.SourcesFileResults
  • Source files that had search resultsSearch results that were found during the recipe run.org.openrewrite.table.SearchResults
  • Source files that errored on a recipeThe details of all errors produced by a recipe run.org.openrewrite.table.SourcesFileErrors
  • Recipe performanceStatistics used in analyzing the performance of recipes.org.openrewrite.table.RecipeRunStats