| /* |
| * Copyright (C) 2015, Google Inc. and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| 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 {@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 |
| } |