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/*******************************************************************************
 * Copyright (c) 2011, 2012 Stephan Herrmann and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Stephan Herrmann - initial API and implementation
 *     IBM Corporation - bug fixes
 *******************************************************************************/
package org.eclipse.jdt.annotation;

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;
 
/**
 * Qualifier for a type in a method signature or a local variable declaration:
 * The entity (return value, parameter, local variable) whose type has this
 * annotation can never have the value null at runtime.
 * 
 * This has two consequences:
 * 

 * Dereferencing the entity is safe, i.e., no NullPointerException can occur at runtime.
 * An attempt to bind a null value to the entity is a compile time error.
 * 
 * For the second case, diagnostics issued by the compiler should distinguish three situations:
 * 
 * Nullness of the value can be statically determined, the entity is definitely bound from either of:
 *     the value null, or
 *         an entity with a {@link Nullable @Nullable} type.
 * Nullness cannot definitely be determined, because different code branches yield different results.
 * Nullness cannot be determined, because other program elements are involved for which
 *     null annotations are lacking.
 * 
 * 
 * @since 1.0
 */
@Documented
@Retention(RetentionPolicy.CLASS)
@Target({ METHOD, PARAMETER, LOCAL_VARIABLE })
public @interface NonNull {
	// marker annotation with no members
}