Allow abnormal page token cases for paging methods

Addresses https://github.com/googleapis/toolkit/issues/692.

Manual changes are in:
lib/google/apis/core/base_service.rb
spec/google/apis/core/service_spec.rb

lib/google/apis/core/base_service.rb

@@ -42,11 +42,12 @@ module Google
         #  True (default) if results should be cached so multiple iterations can be used.
         # @param [Symbol] items
         #   Name of the field in the result containing the items. Defaults to :items
-        def initialize(service, max: nil, items: :items, cache: true, &block)
+        def initialize(service, max: nil, items: :items, cache: true, response_page_token: :next_page_token, &block)
           @service = service
           @block = block
           @max = max
           @items_field = items
+          @response_page_token_field = response_page_token
           if cache
             @result_cache = Hash.new do |h, k|
               h[k] = @block.call(k, @service)
@@ -75,8 +76,9 @@ module Google
               yield items
             end
             break if @max && item_count >= @max
-            break if @last_result.next_page_token.nil? || @last_result.next_page_token == page_token
-            page_token = @last_result.next_page_token
+            next_page_token = @last_result.send(@response_page_token_field)
+            break if next_page_token.nil? || next_page_token == page_token
+            page_token = next_page_token
           end
         end
       end
@@ -270,9 +272,9 @@ module Google
         # @example Retrieve all files,
         #   file_list = service.fetch_all { |token, s| s.list_files(page_token: token) }
         #   file_list.each { |f| ... }
-        def fetch_all(max: nil, items: :items, cache: true,  &block)
+        def fetch_all(max: nil, items: :items, cache: true, response_page_token: :next_page_token, &block)
           fail "fetch_all may not be used inside a batch" if batch?
-          return PagedResults.new(self, max: max, items: items, cache: cache, &block)
+          return PagedResults.new(self, max: max, items: items, cache: cache, response_page_token: response_page_token, &block)
         end
 
         protected

lib/google/apis/version.rb

@@ -15,7 +15,7 @@
 module Google
   module Apis
     # Client library version
-    VERSION = '0.9.26'
+    VERSION = '0.9.27'
 
     # Current operating system
     # @private