http://www.eclipse.org/jgit//org.eclipse.jgit: Repository access and algorithms (Eclipse JGit Project)
  • Eclipse Distribution License (New BSD License)
  • Andrey Loskutov
  • Christian Halstrick
  • Dave Borowitz
  • David Pursehouse
  • Gunnar Wagenknecht
  • Jonathan Nieder
  • Jonathan Tan
  • Matthias Sohn
  • Sasa Zivkov
  • Terry Parker
  • Thomas Wolf 
/*
 * Copyright (C) 2015, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.annotations;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


Marks types that can hold the value null at run time. 
 Unlike org.eclipse.jdt.annotation.Nullable, this has run-time retention, allowing the annotation to be recognized by Guice. Unlike javax.annotation.Nullable, this does not involve importing new classes to a standard (Java EE) package, so it can be deployed in an OSGi container without running into split-package
problems.

 You can use this annotation to qualify a type in a method signature or local variable declaration. The entity whose type has this annotation is allowed to hold the value null at run time. This allows annotation based null analysis to infer that 
    

  • Binding a null value to the entity is legal. 
  • Dereferencing the entity is unsafe and can trigger a NullPointerException. 


 To avoid a dependency on Java 8, this annotation does not use @Target TYPE_USE. That may change when JGit starts requiring Java 8. 

Warning: Please do not use this annotation on arrays. Different annotation processors treat @Nullable Object[] differently: some treat it as an array of nullable objects, for consistency with versions of Nullable defined with @Target TYPE_USE, while others treat it as a nullable array of objects. JGit therefore avoids using this annotation on arrays altogether. 
See Also:
Since:4.2
/**
 * Marks types that can hold the value {@code null} at run time.
 * <p>
 * Unlike {@code org.eclipse.jdt.annotation.Nullable}, this has run-time
 * retention, allowing the annotation to be recognized by
 * <a href="https://github.com/google/guice/wiki/UseNullable">Guice</a>. Unlike
 * {@code javax.annotation.Nullable}, this does not involve importing new classes
 * to a standard (Java EE) package, so it can be deployed in an OSGi container
 * without running into
 * <a href="http://wiki.osgi.org/wiki/Split_Packages">split-package</a>
 * <a href="https://gerrit-review.googlesource.com/50112">problems</a>.
 * <p>
 * You can use this annotation to qualify a type in a method signature or local
 * variable declaration. The entity whose type has this annotation is allowed to
 * hold the value {@code null} at run time. This allows annotation based null
 * analysis to infer that
 * <ul>
 * <li>Binding a {@code null} value to the entity is legal.
 * <li>Dereferencing the entity is unsafe and can trigger a
 * {@code NullPointerException}.
 * </ul>
 * <p>
 * To avoid a dependency on Java 8, this annotation does not use
 * {@link Target @Target} {@code TYPE_USE}. That may change when JGit starts
 * requiring Java 8.
 * <p>
 * <b>Warning:</b> Please do not use this annotation on arrays. Different
 * annotation processors treat {@code @Nullable Object[]} differently: some
 * treat it as an array of nullable objects, for consistency with versions of
 * {@code Nullable} defined with {@code @Target} {@code TYPE_USE}, while others
 * treat it as a nullable array of objects. JGit therefore avoids using this
 * annotation on arrays altogether.
 *
 * @see <a href=
 *      "http://types.cs.washington.edu/checker-framework/current/checker-framework-manual.html#faq-array-syntax-meaning">
 *      The checker-framework manual</a>
 * @since 4.2
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ FIELD, METHOD, PARAMETER, LOCAL_VARIABLE })
public @interface Nullable {
	// marker annotation with no members
}