fix(core): remove rexml from dependencies

Author: dazuma

generated/google-apis-discovery_v1/Gemfile

@@ -21,3 +21,5 @@ platforms :ruby do
     gem "redcarpet", "~> 3.5"
   end
 end
+
+gem "google-apis-core", path: "../../google-apis-core"

google-apis-core/google-apis-core.gemspec

@@ -25,6 +25,6 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency "addressable", "~> 2.5", ">= 2.5.1"
   gem.add_runtime_dependency "mini_mime", "~> 1.0"
   gem.add_runtime_dependency "googleauth", "~> 1.9"
-  gem.add_runtime_dependency "httpclient", ">= 2.8.1", "< 3.a"
-  gem.add_runtime_dependency "rexml"
+  gem.add_runtime_dependency "httpclient", ">= 2.8.3", "< 3.a"
+  gem.add_runtime_dependency "mutex_m" # used by httpclient
 end

google-apis-generator/Gemfile

@@ -36,3 +36,5 @@ platforms :ruby do
     gem 'pry-byebug', '~> 3.2'
   end
 end
+
+gem "google-apis-core", path: "../google-apis-core"

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

@@ -103,7 +103,7 @@ def <%= api_method.generated_name %>(<% for param in api_method.required_paramet
 <% 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? -%>
+<% if api_method.api_version && !api_method.api_version.empty? -%>
   command.set_api_version_header "<%= api_method.api_version %>"
 <% end -%>
   execute_or_queue_command(command, &block)