Bug 73962 [IDE] NPE in CopyFilesAndFoldersOperation when overwriting existing folder
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/wizards/datatransfer/ImportOperation.java
private static final int POLICY_SKIP_CHILDREN = 1;
    private static final int POLICY_FORCE_OVERWRITE = 2;
    private Object source;
    private IPath destinationPath;
    private IContainer destinationContainer;
    private List selectedFiles;
    private List rejectedFiles;
    private IImportStructureProvider provider;
    private IProgressMonitor monitor;
    protected IOverwriteQuery overwriteCallback;
    private Shell context;
    private List errorTable = new ArrayList();
    private boolean createContainerStructure = true;
    
    private static final int OVERWRITE_NOT_SET = 0;
    private static final int OVERWRITE_NONE = 1;
    private static final int OVERWRITE_ALL = 2;
    private int overwriteState = OVERWRITE_NOT_SET;
    /**
     * Creates a new operation that recursively imports the entire contents of the
     * specified root file system object.
     * <p>
     * The <code>source</code> parameter represents the root file system object to 
     * import. All contents of this object are imported. Valid types for this parameter
     * are determined by the supplied <code>IImportStructureProvider</code>.
     * </p>
     * <p>
     * The <code>provider</code> parameter allows this operation to deal with the
     * source object in an abstract way. This operation calls methods on the provider
     * and the provider in turn calls specific methods on the source object.