Merge pull request rails#50489 from maniSHarma7575/50481-fix-activesupport-json-encode

[FIX] Fix Activesupport json encode for hash with duplicate keys

Author: byroot

activesupport/lib/active_support/json/encoding.rb

@@ -76,7 +76,7 @@ def jsonify(value)
             when Hash
               result = {}
               value.each do |k, v|
-                k = k.to_s unless Symbol === k || String === k
+                k = k.to_s unless String === k
                 result[k] = jsonify(v)
               end
               result

activesupport/test/json/encoding_test_cases.rb

@@ -81,7 +81,8 @@ module EncodingTestCases
                      [ [1, "a", :b, nil, false], %([1,\"a\",\"b\",null,false]) ]]
 
     HashTests     = [[ { foo: "bar" }, %({\"foo\":\"bar\"}) ],
-                     [ { 1 => 1, 2 => "a", 3 => :b, 4 => nil, 5 => false }, %({\"1\":1,\"2\":\"a\",\"3\":\"b\",\"4\":null,\"5\":false}) ]]
+                     [ { 1 => 1, 2 => "a", 3 => :b, 4 => nil, 5 => false }, %({\"1\":1,\"2\":\"a\",\"3\":\"b\",\"4\":null,\"5\":false}) ],
+                     [ { "a" => 1, :a => 2, :c => { "b" => 3, :b => 4 } }, %({\"a\":2,\"c\":{\"b\":4}}) ]]
 
     RangeTests    = [[ 1..2,     %("1..2")],
                      [ 1...2,    %("1...2")],