picasawebservice java authentication access denied - google-oauth

Question

My previously working picasawebservice code failed when Google switched to the OAuth 2 authentication.
I have modified the code to use a Goodle credential for which I needed to set up a Service Account.
Although no errors are returned when I add the credential to the PicasawebService object I cannot add any photos to my album.
I have obtained a list of albums using the url https://picasaweb.google.com/data/feed/api/user/xxx?kind=album but it only returns the public Profile Album, not the other albums on the account, also when I use the album id returned by the feed I get an "Access forbidden" error when I try to insert a photo. (xxx - I have used both the user id and the email address for the account and get the same result in each case).
I have been able to establish the alubum ids for the private albums on the account but using these also failed when attempting an insert.
The code is
String emailAddress = "-- the email address from the Google Developers console for the credential --";
JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
GoogleCredential credential = null;
try {
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
String[] SCOPESArray = {"https://picasaweb.google.com/data","http://picasaweb.google.com/data/feed/api"};
final List<String> SCOPES = Arrays.asList(SCOPESArray);
credential = new GoogleCredential.Builder()
.setTransport(httpTransport)
.setJsonFactory(JSON_FACTORY)
.setServiceAccountId(emailAddress)
.setServiceAccountPrivateKeyFromP12File(new File("-- the p12 key file --"))
.setServiceAccountScopes(SCOPES)
.build();
} catch (GeneralSecurityException ex) {
logger.error("processUpload: Error getting Google credential " + accountBean.getZuzzAccountId() + " - " + accountBean.getAccountTitle() + " - " + ex.toString());
uploadMessage = "Error getting a connection to the photo store - please see the administratior";
return;
}
credential.refreshToken();
String accessToken = credential.getAccessToken();
PicasawebService myService = new PicasawebService("Zuzz-ZuzzClub-1.2");
myService.setOAuth2Credentials(credential);
URL albumPostUrl = null;
try {
albumPostUrl = new URL("https://picasaweb.google.com/data/feed/api/user/-- my user id --/albumid/-- album id returned from feed --");
} catch (MalformedURLException ex) {
logger.error("processUpload: Error getting album post url for account " + accountBean.getZuzzAccountId() + " - " + accountBean.getAccountTitle() + " - " + ex.toString());
uploadMessage = "Error getting a connection to the photo store - please see the administratior";
return;
}
PhotoEntry myPhoto = new PhotoEntry();
myPhoto.setTitle(new PlainTextConstruct(fileName));
myPhoto.setDescription(new PlainTextConstruct(months.get(Integer.valueOf(editionMonth).intValue()) + " " + editionYear));
myPhoto.setClient("ZuzzClub");
MediaStreamSource myMedia = null;
myMedia = new MediaStreamSource(imageInStream,"image/jpeg");
if (myMedia == null) {
logger.error("processUpload: Error generating the thumbnail photo - null media source for account " + accountBean.getZuzzAccountId() + " - " + accountBean.getAccountTitle());
uploadMessage = "Error generating the thumbnail photo - please see the administratior";
return;
}
myPhoto.setMediaSource(myMedia);
thumbNailUrl = null;
try {
PhotoEntry returnedPhoto = myService.insert(albumPostUrl, myPhoto);
ArrayList<MediaContent> mediaContent = (ArrayList<MediaContent>) returnedPhoto.getMediaContents();
thumbNailUrl = mediaContent.get(0).getUrl();
} catch (IOException ex) {
logger.error("processUpload: Error adding photo to Photo store for account " + accountBean.getZuzzAccountId() + " - " + accountBean.getAccountTitle() + " - " + ex.toString());
uploadMessage = "Error generating the thumbnail photo - please see the administratior";
return;
} catch (ServiceException ex) {
logger.error("processUpload: Error adding photo to Photo store for account " + accountBean.getZuzzAccountId() + " - " + accountBean.getAccountTitle() + " - " + ex.toString());
uploadMessage = "Error generating the thumbnail photo - please see the administratior";
return;
} finally {
imageInStream.close();
}
The problem appears to be that the authentication has not granted permission to perform the insert, however the service account is set to "Can edit" in the Google Developers Console.
Is there a way of finding out what permissions the service has after the credential has been applied?
Has anyone managed to add photos to a Picasa album after the authentication change?