Bug 20474 [Dialogs] SelectionDialog should not return an initial selection of null
F3 The JavaDoc for SelectionDialog.getInitialSelection does not state that null is a valid return value. If we think that clients are acutally using the null case to avoid performing some real work then we should fix the javadoc. Otherwise we should an empty list.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/dialogs/MultiElementListSelectionDialog.java
}
	
	/**
	 * Sets the elements to be displayed in the dialog.
	 * @param elements an array of pages holding arrays of elements
	 */
	public void setElements(Object[][] elements) {
		fNumberOfPages= elements.length;			
		fPages= new Page[fNumberOfPages];
		for (int i= 0; i != fNumberOfPages; i++)
			fPages[i]= new Page(elements[i]);
		
		initializeResult(fNumberOfPages);
	}
	/*
	 * @see Window#open()
	 */
	public int open() {
		List selection= getInitialSelections();
		if (selection == null) {
			setInitialSelections(new Object[fNumberOfPages]);
			selection= getInitialSelections();
		}
			
		Assert.isTrue(selection.size() == fNumberOfPages);
		
		return super.open();
	}
		 
	/**