Bug 29698 drag and drop of java files between packages in package explorer doesn't work
the <preview> <ok> <cancel> dialog shows up, but <ok> has the same effect as <cancel> and <preview> would only show movements of files and no changes in imports of other java files. on <ok> in the preview it only moves the file(s) (as indicated ) without changing referencing imports.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/refactoring/RenameSupport.java
* value indicating that no new name is provided.
	 * @param flags flags controlling additional parameters. Valid flags are
	 * <code>UPDATE_REFERENCES</code> or <code>NONE</code>.
	 * @return the <tt>RenameSupport</tt>.
	 * @throws CoreException if an unexpected error occured while creating
	 * the <tt>RenameSupport</tt>.
	 */
	public static RenameSupport create(IJavaProject project, String newName, int flags) throws CoreException {
		RefactoringSupport.JavaProject support= new RefactoringSupport.JavaProject(project);
		RenameJavaProjectRefactoring refactoring= support.getSpecificRefactoring();
		setNewName(refactoring, newName);
		refactoring.setUpdateReferences(updateReferences(flags));
		return new RenameSupport(support, project);
	}
	
	/**
	 * Creates a new rename support for the given <tt>IPackageFragmentRoot</tt>.
	 * 
	 * @param root the <tt>IPackageFragmentRoot</tt> to be renamed.
	 * @param newName the package fragment roor's new name. <code>null</code> is
	 * a valid value indicating that no new name is provided.
	 * @return the <tt>RenameSupport</tt>.
	 * @throws CoreException if an unexpected error occured while creating
	 * the <tt>RenameSupport</tt>.
	 */
	public static RenameSupport create(IPackageFragmentRoot root, String newName) throws CoreException {
		RefactoringSupport.SourceFolder support= new RefactoringSupport.SourceFolder(root);
		RenameSourceFolderRefactoring refactoring= support.getSpecificRefactoring();
		setNewName(refactoring, newName);
		return new RenameSupport(support, root);