How can I use Google GSON to deserialize a JSON array into a a Collection of a generic type?

I'm writing some code that is going to be used to retrieve resources from a website. It all sort of looks like this: ``` public Collection<Project> getProjects() { String json = getJsonData(methods.get(Project.class)); //Gets a json list, ie [1, 2, 3, 4] Gson gson = new Gson(); Type collectionType = new TypeToken<Collection<Project>>() {}.getType(); return gson.fromJson(json, collectionType); } ``` So naturally I tried abstracting it using Java generics. ``` /* * Deserialize a json list and return a collection of the given type. * * Example usage: getData(AccountQuota.class) -> Collection<AccountQuota> */ @SuppressWarnings("unchecked") public <T> Collection<T> getData(Class<T> cls) { String json = getJsonData(methods.get(cls)); //Gets a json list, ie [1, 2, 3, 4] Gson gson = new Gson(); Type collectionType = new TypeToken<Collection<T>>(){}.getType(); return (Collection<T>) gson.fromJson(json, collectionType); } ``` The generic version of the code doesn't quite work though. ``` public void testGetItemFromGetData() throws UserLoginError, ServerLoginError { Map<String,String> userData = GobblerAuthenticator.authenticate("foo@example.com", "mypassword"); String client_key = userData.get("client_key"); GobblerClient gobblerClient = new GobblerClient(client_key); ArrayList<Project> machines = new ArrayList<Project>(); machines.addAll(gobblerClient.getData(Project.class)); assertTrue(machines.get(0).getClass() == Project.class); Log.i("Machine", gobblerClient.getData(Project.class).toString()); } java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.gobbler.synchronization.Machine at com.gobblertest.GobblerClientTest.testGetItemFromGetData(GobblerClientTest.java:53) at java.lang.reflect.Method.invokeNative(Native Method) at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169) at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154) at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:545) at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1551) ``` The class in question: ``` import java.util.Map; public class Project { private int total_bytes_stored; private String name; private String user_data_guid; private int seqnum; private String guid; private Map current_checkpoint; private Map<String, String> upload_folder; // TODO: schema_version private boolean deleted; // TODO: download_folders public Project() {} // No args constructor used for GSON } ``` I'm not quite familiar with all the details of Java generics or GSON internals and my search has not been particularly informative. There a bunch of questions here on SO, but most refer to implementing methods like the original one I had. And the GSON docs don't seem to cover this particular case. So again, how can I use Google GSON to deserialize a JSON array into a a Collection of a generic type?