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prohibitNonJSpecifyAnnotations

Category: Rules Reference
Scope: Fields, Methods, Parameters, Record components, Type parameters
Purpose: Enforces the usage of standard JSpecify nullness annotations by prohibiting others.

What does it check?​

The prohibitNonJSpecifyAnnotations rule scans the bytecode for specific nullness annotations that come from libraries other than JSpecify.

If it detects any of the following annotations, it reports an error:

  • javax.annotation.Nullable / Nonnull (JSR-305)
  • jakarta.annotation.Nullable / Nonnull
  • org.jetbrains.annotations.Nullable / NotNull
  • org.eclipse.jdt.annotation.Nullable / NonNull
  • edu.umd.cs.findbugs.annotations.Nullable / NonNull
  • org.checkerframework.checker.nullness.qual.Nullable / NonNull
  • org.springframework.lang.Nullable / NonNull

The rule checks usage on:

  • Class/Interface/Record declarations
  • Fields
  • Method
  • Method return type
  • Method parameters
  • Record components
  • Generic type arguments (e.g., List<@NotNull String>)

Why is it important?​

  • Standardization: Prevents a mix of different annotation libraries in the same project, which can be confusing for developers.
  • Tooling Compatibility: JSpecify is the standard for nullness in Java. Migrating to it ensures better compatibility with modern build tools and IDEs.
  • Clarity: JSpecify annotations have well-defined semantics regarding nullness, unlike some older libraries (e.g., JSR-305) which can be ambiguous (e.g., javax.annotation.Nullable vs javax.annotation.CheckForNull).

Examples​

❌ Invalid Example: Using JetBrains annotations​

import org.jetbrains.annotations.Nullable;

public class UserEntity {

  @Nullable
  private String nickname; // error
}

Problems detected:

[ERROR] UserEntity#nickname: Prohibited nullable annotation found on field: org.jetbrains.annotations.Nullable.

❌ Invalid Example: Using JSR-305 annotations​

import javax.annotation.Nonnull;

public class UserEntity {

  @Nonnull
  public String getName() { // error
    return "Alice";
  }
}

Problems detected:

[ERROR] UserEntity#getName(): Prohibited nullable annotation found on method: javax.annotation.Nonnull.

✅ Valid Example: Using JSpecify​

import org.jspecify.annotations.Nullable;

public class UserEntity {

  @Nullable
  private String nickname;
}

How to configure it?​

You can enable the prohibitNonJSpecifyAnnotations rule by adding it to your plugin configuration:


<configuration>
  <rules>
    <prohibitNonJSpecifyAnnotations/>
  </rules>
</configuration>

Optional parameters:

ParameterTypeDefaultDescription
exclusionsFileString(none)Path to a text file listing classes to exclude, see Exclusions File Format

When to enable?​

Recommended for:

  • New projects: Start with a clean slate and allow only JSpecify from day one.
  • Migration phase: When you decide to switch to JSpecify and want to prevent new "pollution" with old annotations while refactoring.

Limitations​

  • This rule strictly checks for the fully qualified class name (FQCN) of the annotation. It doesn't analyze the semantics or meta-annotations.
  • It doesn't automatically fix or replace the annotations; it only reports them.