org.springframework.lang.Nullable Maven / Gradle / Ivy
/*
* Copyright 2002-2019 the original author or authors.
*
* 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
*
* https://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.
*/
package org.springframework.lang;
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;
import javax.annotation.Nonnull;
import javax.annotation.meta.TypeQualifierNickname;
import javax.annotation.meta.When;
/**
* A common Spring annotation to declare that annotated elements can be {@code null} under
* some circumstance.
*
* Leverages JSR-305 meta-annotations to indicate nullability in Java to common
* tools with JSR-305 support and used by Kotlin to infer nullability of Spring API.
*
*
Should be used at parameter, return value, and field level. Methods override should
* repeat parent {@code @Nullable} annotations unless they behave differently.
*
*
Can be used in association with {@code @NonNullApi} or {@code @NonNullFields} to
* override the default non-nullable semantic to nullable.
*
* @author Sebastien Deleuze
* @author Juergen Hoeller
* @since 5.0
* @see NonNullApi
* @see NonNullFields
* @see NonNull
*/
@Target({ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Nonnull(when = When.MAYBE)
@TypeQualifierNickname
public @interface Nullable {
}