public MutableFile updateFile(final String fileIdentifier) {
Validate.notNull(fileIdentifier, "File identifier required");
final File actual = new File(fileIdentifier);
Validate.isTrue(actual.exists(), "File '%s' does not exist",
fileIdentifier);
new UpdateFile(undoManager, filenameResolver, actual);
final ManagedMessageRenderer renderer = new ManagedMessageRenderer(
filenameResolver, actual, false);
renderer.setIncludeHashCode(processManager.isDevelopmentMode());
return new DefaultMutableFile(actual, fileMonitorService, renderer);
}