[X-Pack] Update specs for http headers

Author: picandocodigo

elasticsearch-xpack/spec/xpack/data_frame/update_data_frame_transform_spec.rb

@@ -12,7 +12,7 @@
         '_data_frame/transforms/foo/_update',
         params,
         {},
-        nil
+        {}
     ]
   end
 

elasticsearch-xpack/spec/xpack/machine_learning/set_upgrade_mode_spec.rb

@@ -12,7 +12,7 @@
        '_ml/set_upgrade_mode',
        {},
        nil,
-       nil
+       {}
     ]
   end
 
@@ -28,7 +28,7 @@
         '_ml/set_upgrade_mode',
         { enabled: true, timeout: '10m' },
         nil,
-        nil
+        {}
       ]
     end
 

elasticsearch-xpack/spec/xpack/security/create_api_key_spec.rb

@@ -12,7 +12,7 @@
         '_security/api_key',
         {},
         body,
-        nil
+        {}
     ]
   end
 
@@ -55,7 +55,7 @@
           '_security/api_key',
           { refresh: 'wait_for' },
           body,
-          nil
+          {}
       ]
     end
 

elasticsearch-xpack/spec/xpack/security/get_api_key_spec.rb

@@ -12,7 +12,7 @@
         '_security/api_key',
         params,
         nil,
-        nil
+        {}
     ]
   end
 

elasticsearch-xpack/spec/xpack/security/get_builtin_privileges_spec.rb

@@ -12,7 +12,7 @@
         '_security/privilege/_builtin',
         {},
         nil,
-        nil
+        {}
     ]
   end
 

elasticsearch-xpack/spec/xpack/security/invalidate_api_key_spec.rb

@@ -12,7 +12,7 @@
         '_security/api_key',
         {},
         body,
-        nil
+        {}
     ]
   end