org.cache2k.annotation.NonNullApi Maven / Gradle / Ivy
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package org.cache2k.annotation;
/*
* #%L
* cache2k API
* %%
* Copyright (C) 2000 - 2021 headissue GmbH, Munich
* %%
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* #L%
*/
import kotlin.annotations.jvm.MigrationStatus;
import kotlin.annotations.jvm.UnderMigration;
import javax.annotation.Nonnull;
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;
import java.lang.annotation.Target;
/**
* Sets the convention to non null parameters and return values on a package level.
* We basically use that everywhere since its a common convention and implied
* by tools like NullAway. However, we need to formally define it in the API
* so Kotlin can infer the nullability correctly.
*
* This uses the {@code @TypeQualifierDefault} from JSR305, which is also recognized by
* Kotlin. Unfortunately Kotlin does not support the {@code @DefaultQualifiers} annotation from
* the checker framework. For best tooling support we annotate the packages with both
* annotations. An alternative would be to annotate @NonNull instead of having the default
* convention Non-null except locals (NNEL).
*
* @author Jens Wilke
* @see
* @see
* @see
* @see
* @see
*/
@Target(value = {ElementType.PACKAGE, ElementType.TYPE})
@Retention(value = RetentionPolicy.CLASS)
@Documented
@Nonnull
@TypeQualifierDefault(value = {ElementType.METHOD, ElementType.PARAMETER})
@UnderMigration(status = MigrationStatus.STRICT)
public @interface NonNullApi { }