```ruby
module HubbleApiClient
  # @api private
  module Connection
    class Base

    private

      def self.get_http_request(uri)
        request = Net::HTTP::Get.new(uri.request_uri)
        assign_headers(request)
      end

      def self.post_http_request(uri, body)
        request = Net::HTTP::Post.new uri
        request.body = body.to_json
        assign_headers(request)
      end

      def self.response_for(http_request, uri)
        response = Net::HTTP.start(uri.host, 443, use_ssl: true) do |http|
          http.request http_request
        end
        response
      rescue SocketError => e
        raise ConnectionError, e.message
      end

      def self.assign_headers(request)
        headers.each_key do |header|
          request[header] = headers[header]
        end
        request
      end

      def self.headers
        {"Authorization" => "Bearer #{app_access_token}"}
      end
    end
  end
end
```

Add Content-Type header from JSON API spec
user
```ruby
module HubbleApiClient
  # @api private
  module Connection
    class Base

    private

      def self.get_http_request(uri)
        request = Net::HTTP::Get.new(uri.request_uri)
        assign_headers(request)
      end

      def self.post_http_request(uri, body)
        request = Net::HTTP::Post.new uri
        request.body = body.to_json
        assign_headers(request)
      end

      def self.response_for(http_request, uri)
        response = Net::HTTP.start(uri.host, 443, use_ssl: true) do |http|
          http.request http_request
        end
        response
      rescue SocketError => e
        raise ConnectionError, e.message
      end

      def self.assign_headers(request)
        headers.each_key do |header|
          request[header] = headers[header]
        end
        request
      end

      def self.headers
        {"Authorization" => "Bearer #{app_access_token}",
         "Content-Type" => "application/vnd.api+json"}
      end
    end
  end
end
```
assistant