Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2

Response you are getting is in object form i.e.

{ 
  "dstOffset" : 3600, 
  "rawOffset" : 36000, 
  "status" : "OK", 
  "timeZoneId" : "Australia/Hobart", 
  "timeZoneName" : "Australian Eastern Daylight Time" 
}

Replace below line of code :

List<Post> postsList = Arrays.asList(gson.fromJson(reader,Post.class))

with

Post post = gson.fromJson(reader, Post.class);

You state in the comments that the returned JSON is this:

{ 
  "dstOffset" : 3600, 
  "rawOffset" : 36000, 
  "status" : "OK", 
  "timeZoneId" : "Australia/Hobart", 
  "timeZoneName" : "Australian Eastern Daylight Time" 
}

You're telling Gson that you have an array of Post objects:

List<Post> postsList = Arrays.asList(gson.fromJson(reader,
                    Post[].class));

You don't. The JSON represents exactly one Post object, and Gson is telling you that.

Change your code to be:

Post post = gson.fromJson(reader, Post.class);