feat: Introduce api_version to discovery clients

google-apis-core/lib/google/apis/core/http_command.rb

@@ -348,6 +348,12 @@ def allow_form_encoding?
           [:post, :put].include?(method) && body.nil?
         end
 
+        # Set the API version header for the service if not empty.
+        # @return [void]
+        def set_api_version_header api_version
+          self.header['X-Goog-Api-Version'] = api_version unless api_version.empty?
+        end
+
         private
 
         UNSAFE_CLASS_NAMES = [

google-apis-core/spec/google/apis/core/http_command_spec.rb

@@ -528,6 +528,16 @@ class SecretPayload
     command.execute(client)
   end
 
+  it 'should set X-Goog-Api-Version headers when requested' do
+    command = Google::Apis::Core::HttpCommand.new(:get, 'https://www.googleapis.com/zoo/animals')
+    command.set_api_version_header "v1_20240502"
+    stub_request(:get, 'https://www.googleapis.com/zoo/animals').to_return(body: %(Api version))
+    result = command.execute(client)
+    expect(a_request(:get, 'https://www.googleapis.com/zoo/animals')
+      .with { |req| req.headers['X-Goog-Api-Version'] == 'v1_20240502' }).to have_been_made
+    expect(result).to eql "Api version"
+  end
+
   describe "#safe_pretty_representation" do
     let(:command) do
       Google::Apis::Core::HttpCommand.new(:get, 'https://www.googleapis.com/zoo/animals')

google-apis-generator/lib/google/apis/generator.rb

@@ -18,6 +18,7 @@
 require 'google/apis/generator/template'
 require 'google/apis/generator/updater'
 require 'google/apis/generator/version'
+require 'google/apis/generator/patch'
 require 'active_support'
 require 'active_support/core_ext'
 require 'active_support/inflector'

google-apis-generator/lib/google/apis/generator/patch.rb

@@ -0,0 +1,33 @@
+require 'google/apis/discovery_v1'
+
+# Extend the DiscoveryV1 API classes with additional fields for code generation,
+# supporting features which are not present in the schema itself.
+module Google
+  module Apis
+    module DiscoveryV1
+      class RestMethod
+        # The `apiVersion` for this method, or empty if not present.
+        # @return [String]
+        attr_accessor :api_version
+
+        # @private
+        # The original DiscoveryV1::RestMethod `update!` method to be called
+        # after applying patches to this schema.
+        alias_method :update_discovery!, :update!
+
+        # Update properties of this object.
+        def update!(**args)
+          @api_version = args.key?(:api_version) ? args[:api_version] : ""
+          update_discovery!(**args)
+        end
+
+        # @private
+        class Representation
+          # @private
+          # The api_version based on the JSON key value.
+          property :api_version, as: 'apiVersion'
+        end
+      end
+    end
+  end
+end

google-apis-generator/lib/google/apis/generator/templates/_method.tmpl

@@ -102,6 +102,9 @@ def <%= api_method.generated_name %>(<% for param in api_method.required_paramet
 <% end -%>
 <% for param in api.parameters.values.reject {|p| p.name == 'key'} -%>
   command.query['<%= param.name %>'] = <%= param.generated_name %> unless <%= param.generated_name %>.nil?
+<% end -%>
+<% unless api_method.api_version.empty? -%>
+  command.set_api_version_header "<%= api_method.api_version %>"
 <% end -%>
   execute_or_queue_command(command, &block)
 end