Bug 15586 Warn the user when a project without the Java nature is opened
When opening a closed project that doesn't have the Java nature when opened, then we should inform the user that the opened project will not appear in the packages view.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/OpenProjectAction.java
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 * Copyright (c) 2002 International Business Machines Corp. and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v0.5 
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v05.html
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 * Contributors:
 *     IBM Corporation - initial API and implementation
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package org.eclipse.jdt.ui.actions;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.dialogs.Dialog;