Ok found the solution:
IFileItemHandle fileItemHandle = (IFileItemHandle) IFileItem.ITEM_TYPE.createItemHandle(change.afterState().getItemId(), change.afterState().getStateId());
file = versionableManager.fetchCompleteState(fileItemHandle, monitor);
if (file instanceof IFolder) {
IFolder folder = (IFolder) file;
relativePath = getFilePath(file, workspaceConnection.configuration(changeSet.getComponent()), monitor);
fileName = folder.getName();
} else {
relativePath = getFilePath(file, workspaceConnection.configuration(changeSet.getComponent()), monitor);
fileName = ((FileItem) file).getName();
}
But still having isses with resolving file path. Anyways this is a big step.