How to manipulate Gson parsing the awesome way. Based on the SO thread: http://stackoverflow.com/questions/11271375/gson-custom-seralizer-for-one-variable-of-many-in-an-object-using-typeadapter

CustomizedTypeAdapterFactory.java

public abstract class CustomizedTypeAdapterFactory<C>
        implements TypeAdapterFactory {
    private final Class<C> customizedClass;

    public CustomizedTypeAdapterFactory(Class<C> customizedClass) {
        this.customizedClass = customizedClass;
    }

    @SuppressWarnings("unchecked") // we use a runtime check to guarantee that 'C' and 'T' are equal
    public final <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
        return type.getRawType() == customizedClass
                ? (TypeAdapter<T>) customizeMyClassAdapter(gson, (TypeToken<C>) type)
                : null;
    }

    private TypeAdapter<C> customizeMyClassAdapter(Gson gson, TypeToken<C> type) {
        final TypeAdapter<C> delegate = gson.getDelegateAdapter(this, type);
        final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
        return new TypeAdapter<C>() {
            @Override public void write(JsonWriter out, C value) throws IOException {
                JsonElement tree = delegate.toJsonTree(value);
                beforeWrite(value, tree);
                elementAdapter.write(out, tree);
            }
            @Override public C read(JsonReader in) throws IOException {
                JsonElement tree = elementAdapter.read(in);
                afterRead(tree);
                return delegate.fromJsonTree(tree);
            }
        };
    }

    /**
     * Override this to muck with {@code toSerialize} before it is written to
     * the outgoing JSON stream.
     */
    protected void beforeWrite(C source, JsonElement toSerialize) {
    }

    /**
     * Override this to muck with {@code deserialized} before it parsed into
     * the application type.
     */
    protected void afterRead(JsonElement deserialized) {
    }
}

DeviceInfo.java

public class DeviceInfo {

    @SerializedName("values")
    private Values mValues;

    private static class Values {
        @SerializedName("Websocket Version")
        private String mWebsocketVersion;

        @SerializedName("Model")
        private String mModel;

        @SerializedName("Machine Type")
        private String mMachineType;

        @SerializedName("Equipment Key")
        private String mEquipmentKey;

        @SerializedName("Part Number")
        private String mPartNumber;

        @SerializedName("Version")
        private String mVersion;

        @SerializedName("Machine UUID")
        private String mMachineUUID;

        @SerializedName("Features")
        private String mFeatures;

        private List<String> mFeatureList;

    }

    //getters and setters ...
    
    public static class DeviceInfoDeserializerFactory extends CustomizedTypeAdapterFactory<Values> {

        public DeviceInfoDeserializerFactory() {
            super(Values.class);
        }

        @Override
        protected void afterRead(JsonElement deserialized) {
            JsonObject machineInfoObject = deserialized.getAsJsonObject();
            String featuresString = machineInfoObject.get("Features").getAsString();
            List<String> features = new ArrayList<String>(Arrays.asList(featuresString.split(", ")));
            JsonArray featureArray = new JsonArray();
            for (String feature : features) {
                featureArray.add(new JsonPrimitive(feature));
            }
            machineInfoObject.add("mFeatureList", featureArray);
        }
    }
}

DeviceInfo.json

{
    "values": {
        "Websocket Version": "2.1",
        "Model": "ETEP14112",
        "Machine Type": ,
        "Equipment Key": "T7",
        "Part Number": "324974",
        "Version": "3.1.1102.0",
        "Machine UUID": "7001004d-4d43-3034-4744-1408e584be00",
        "Features": "Feature 1, Feature 2, Feature 3, Feature 4, Feature 5, Feature 6"
    }
}

MachineInfoParseTest.java

public class MachineInfoParseTest extends TestCase {

    private String mManifest_1 = "{ \"values\":{ \"Websocket Version\":\"2.1\", \"Model\":\"ETEP14112\", \"Machine Type\":\"SpecialDevice\", \"Equipment Key\":\"T7\", \"Part Number\":\"324974\", \"Version\":\"3.1.1102.0\", \"Machine UUID\":\"7001004d-4d43-3034-4744-1408e584be00\", \"Features\":\"Feature 1, Feature 2, Feature 3, Feature 4, Feature 5, Feature 6\"}}";

    public void testManifestParse() {
        Gson gson = new GsonBuilder().registerTypeAdapterFactory(new MachineInfo.MachineInfoDeserializerFactory()).create();
        MachineInfo machineInfo = gson.fromJson(mManifest_1, MachineInfo.class);
        List<String> featureList = machineInfo.getFeatureList();
        assertNotNull(featureList);
        assertEquals(6, featureList.size());
        assertEquals("Feature 1", featureList.get(0));
    }
}