PackageNullable.java

package com.example.util.nullability;

import javax.annotation.Nullable;
import javax.annotation.meta.TypeQualifierDefault;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

/**
 * This annotation can be applied to a package, class or method to indicate that the class fields, method return types and parameters in
 * that element are nullable by default unless:
 * - The method overrides a method in a superclass (in which case the annotation of the corresponding parameter in the superclass applies).
 * - There is a default parameter annotation applied to a more tightly nested element.
 */
@Documented
@Nullable
@TypeQualifierDefault(
        {
                ElementType.ANNOTATION_TYPE,
                ElementType.CONSTRUCTOR,
                ElementType.FIELD,
                ElementType.LOCAL_VARIABLE,
                ElementType.METHOD,
                ElementType.PACKAGE,
                ElementType.PARAMETER,
                ElementType.TYPE
        })
@Retention(RetentionPolicy.RUNTIME)
public @interface PackageNullable {

}