Impact of Shift_JIS Charset Changes on External Service Requests

Salesforce has been mapping the Shift_JIS charset alias to the Windows-31J definition. However, this mapping will be discontinued in Spring'25.
For customers using External Services to make a callout with form parameters using the content type application/x-www-form-urlencoded; charset=Shift_JIS or any Shift_JIS alias, the encoding of form parameters will differ from the previous behavior.

Shift_JIS will be treated as its own character set. As a result, if characters not part of the Shift_JIS character set are used in form parameters with charset=Shift_JIS or any Shift_JIS alias in External Services, they will be sent differently.

For example, when the schema of an External Service is as follows:

"/form-in-sjis": {
  "post": {
	"consumes": [
	  "application/x-www-form-urlencoded; charset=Shift_JIS"
	],
	"produces": [
	  "application/x-www-form-urlencoded"
	],
	"parameters": [{
		"name": "enclosedCJK",
		"in": "formData",
		"type": "string"
	  },
	  {
		"name": "circledNum",
		"in": "formData",
		"type": "string"
	  },
	  {
		"name": "fullWidthMinus",
		"in": "formData",
		"type": "string"
	  }
	],

If characters such as ① (circled number), ㈱ (enclosed CJK character), and － (full-width minus) are used as parameter values, they are currently sent in the following request body using Windows-31J encoding.

enclosedCJK=%87%8A&circledNum=%87%40&fullWidthMinus=%81%7C

The request body will appear as follows after the change.

enclosedCJK=%3F&circledNum=%3F&fullWidthMinus=%3F