Updated Cask::Cask#to_h to call Conflicts#to_h instead of to_a. Updated ConflictsWith#to_h to iterate over VALID_KEYS.

Library/Homebrew/cask/cask.rb

@@ -133,7 +133,7 @@ module Cask
         end,
         "caveats"        => caveats,
         "depends_on"     => depends_on,
-        "conflicts_with" => conflicts_with.to_a,
+        "conflicts_with" => conflicts_with.to_h,
         "container"      => container,
         "auto_updates"   => auto_updates,
       }

Library/Homebrew/cask/dsl/conflicts_with.rb

@@ -26,10 +26,8 @@ module Cask
         end
       end
 
-      def to_a
-        conflicts={}
-        @pairs.each { |k, v| conflicts[k]=v }
-        conflicts
+      def to_h
+        Hash[VALID_KEYS.map { |key| [key, instance_variable_get("@#{key}").to_a] }]
       end
     end
   end