Handle recursive hashes (#621)

This fixes the generator for cases where one of the entries of the
"schemas" object returned by the Discovery service is a recursively
defined map.

Fixes #608

lib/google/apis/generator/model.rb

@@ -55,8 +55,14 @@ module Google
             return 'Fixnum' if format == 'uint64'
             return TYPE_MAP[type]
           when 'array'
+            if items == self
+              return sprintf('Array<%s>', qualified_name)
+            end
             return sprintf('Array<%s>', items.generated_type)
           when 'hash'
+            if additional_properties == self
+              return sprintf('Hash<String,%s>', qualified_name)
+            end
             return sprintf('Hash<String,%s>', additional_properties.generated_type)
           when 'object'
             return qualified_name
@@ -81,16 +87,16 @@ module Google
           return [] if parameters.nil?
           parameters.values.select { |param| param.location == 'query' }
         end
-        
+
         def required_parameters
           return [] if parameter_order.nil? || parameters.nil?
           parameter_order.map { |name| parameters[name] }.select { |param| param.location == 'path' || param.required }
         end
-        
+
         def optional_query_parameters
           query_parameters.select { |param| param.required != true }
         end
-        
+
       end
 
       class RestResource

lib/google/apis/generator/templates/_class.tmpl

@@ -1,4 +1,4 @@
-<% if cls.type == 'object' -%>
+<% if cls.type == 'object' || (cls.type == 'hash' && cls.properties.length > 0) -%>
 
 # <%= block_comment(cls.description, 0, 1) %>
 class <%= cls.generated_class_name %><% if cls.base_ref %> < <%= cls.base_ref.generated_type %><% end %>

spec/fixtures/files/test_api.json

@@ -90,6 +90,9 @@
         "hat": {
           "$ref": "Hat"
         },
+        "recursiveHat": {
+          "$ref": "RecursiveHat"
+        },
         "properties": {
           "$ref": "HashLikeThing"
         },
@@ -131,6 +134,49 @@
         ]
       }
     },
+    "RecursiveHat": {
+      "id": "RecursiveHat",
+      "type": "object",
+      "properties": {
+        "bool": {
+          "type": "boolean",
+          "description": "The bool value."
+        },
+        "double": {
+          "type": "number",
+          "description": "The double value.",
+          "format": "double"
+        },
+        "image": {
+          "$ref": "Image",
+          "description": "The image value."
+        },
+        "int": {
+          "type": "integer",
+          "description": "The int value.",
+          "format": "int32"
+        },
+        "kind": {
+          "type": "string",
+          "description": "The kind, fixed to \"test#recursiveHat\".",
+          "default": "test#recursiveHat"
+        },
+        "list": {
+          "type": "array",
+          "description": "The list of typed values.",
+          "items": {
+            "$ref": "RecursiveHat"
+          }
+        },
+        "string": {
+          "type": "string",
+          "description": "The string value."
+        }
+      },
+      "additionalProperties": {
+        "$ref": "RecursiveHat"
+      }
+    },
     "TopHat": {
       "type": "object",
       "properties": {