Changed .rack3? to .lowercase_headers?

lib/grape.rb

@@ -42,8 +42,8 @@ def self.deprecator
     @deprecator ||= ActiveSupport::Deprecation.new('2.0', 'Grape')
   end
 
-  def self.rack3?
-    Gem::Version.new(::Rack.release) >= Gem::Version.new('3')
+  def self.lowercase_headers?
+    Rack::CONTENT_TYPE == 'content-type'
   end
 
   eager_autoload do

lib/grape/http/headers.rb

@@ -11,7 +11,7 @@ module Headers
       REQUEST_METHOD  = 'REQUEST_METHOD'
       QUERY_STRING    = 'QUERY_STRING'
 
-      if Grape.rack3?
+      if Grape.lowercase_headers?
         ALLOW             = 'allow'
         CACHE_CONTROL     = 'cache-control'
         CONTENT_LENGTH    = 'content-length'

lib/grape/request.rb

@@ -46,7 +46,7 @@ def build_headers
       end
     end
 
-    if Grape.rack3?
+    if Grape.lowercase_headers?
       def transform_header(header)
         -header[5..].tr('_', '-').downcase
       end

spec/grape/api/custom_validations_spec.rb

@@ -169,12 +169,12 @@ def validate(request)
         end
 
         def access_header
-          Grape.rack3? ? 'x-access-token' : 'X-Access-Token'
+          Grape.lowercase_headers? ? 'x-access-token' : 'X-Access-Token'
         end
       end
     end
     let(:app) { Rack::Builder.new(subject) }
-    let(:x_access_token_header) { Grape.rack3? ? 'x-access-token' : 'X-Access-Token' }
+    let(:x_access_token_header) { Grape.lowercase_headers? ? 'x-access-token' : 'X-Access-Token' }
 
     before do
       described_class.register_validator('admin', admin_validator)

spec/grape/endpoint_spec.rb

@@ -146,15 +146,15 @@ def app
 
     it 'includes additional request headers' do
       get '/headers', nil, 'HTTP_X_GRAPE_CLIENT' => '1'
-      x_grape_client_header = Grape.rack3? ? 'x-grape-client' : 'X-Grape-Client'
+      x_grape_client_header = Grape.lowercase_headers? ? 'x-grape-client' : 'X-Grape-Client'
       expect(JSON.parse(last_response.body)[x_grape_client_header]).to eq('1')
     end
 
     it 'includes headers passed as symbols' do
       env = Rack::MockRequest.env_for('/headers')
       env[:HTTP_SYMBOL_HEADER] = 'Goliath passes symbols'
       body = read_chunks(subject.call(env)[2]).join
-      symbol_header = Grape.rack3? ? 'symbol-header' : 'Symbol-Header'
+      symbol_header = Grape.lowercase_headers? ? 'symbol-header' : 'Symbol-Header'
       expect(JSON.parse(body)[symbol_header]).to eq('Goliath passes symbols')
     end
   end

spec/grape/request_spec.rb

@@ -90,7 +90,7 @@ module Grape
           }
         end
         let(:x_grape_is_cool_header) do
-          Grape.rack3? ? 'x-grape-is-cool' : 'X-Grape-Is-Cool'
+          Grape.lowercase_headers? ? 'x-grape-is-cool' : 'X-Grape-Is-Cool'
         end
 
         it 'cuts HTTP_ prefix and capitalizes header name words' do
@@ -120,7 +120,7 @@ module Grape
           default_env.merge(request_headers)
         end
         let(:grape_likes_symbolic_header) do
-          Grape.rack3? ? 'grape-likes-symbolic' : 'Grape-Likes-Symbolic'
+          Grape.lowercase_headers? ? 'grape-likes-symbolic' : 'Grape-Likes-Symbolic'
         end
 
         it 'converts them to string' do