反序列化

json array反序列化为 java List<T>

https://stackoverflow.com/questions/19796590/com-google-gson-internal-linkedhashtreemap-cannot-be-cast-to-my-object

HashMap<String, FeatureDetails> featuresFromJson = 
new Gson().fromJson(JSONFeatureSet, new TypeToken<Map<String,FeatureDetails>>() {}.getType());