}
public OAuth2AccessToken obtainAccessToken(OAuth2ProtectedResourceDetails resource, AccessTokenRequest request)
throws UserRedirectRequiredException, AccessDeniedException {
OAuth2AccessToken accessToken = null;
OAuth2AccessToken existingToken = null;
Authentication auth = SecurityContextHolder.getContext().getAuthentication();
if (auth instanceof AnonymousAuthenticationToken) {
if (!resource.isClientOnly()) {
throw new InsufficientAuthenticationException(
"Authentication is required to obtain an access token (anonymous not allowed)");
}
}
if (resource.isClientOnly() || (auth != null && auth.isAuthenticated())) {
existingToken = request.getExistingToken();
if (existingToken == null && clientTokenServices != null) {
existingToken = clientTokenServices.getAccessToken(resource, auth);
}
if (existingToken != null) {
if (existingToken.isExpired()) {
if (clientTokenServices != null) {
clientTokenServices.removeAccessToken(resource, auth);
}
OAuth2RefreshToken refreshToken = existingToken.getRefreshToken();
if (refreshToken != null) {
accessToken = refreshAccessToken(resource, refreshToken, request);
}
}
else {