in java/com/google/devtools/bazel/e4b/wizard/DirectoryTreeContentProvider.java [181:187]
static void setFileTreeRoot(CheckboxTreeViewer tv, File root) {
DirectoryTreeContentProvider provider = (DirectoryTreeContentProvider) tv.getContentProvider();
if ((root == null && provider.getRoot() != null) || !root.equals(provider.getRoot())) {
provider.setRoot(root);
tv.refresh();
}
}