Inaccurate schema for the app_id property in the application-passwords endpoints

[johnbillion]

The schema for the app_id property of objects in the wp/v2/application-passwords/* endpoints has a format of uuid. This is not entirely accurate because if no app ID was provided when the application password was registered then this field contains an empty string.

Trac ticket: https://core.trac.wordpress.org/ticket/53692

Needs tests.

…rtelated unit test

Trac ticket: https://core.trac.wordpress.org/ticket/53692
Reference PR: ​https://github.com/WordPress/wordpress-develop/pull/1507

Closing in favour of #8282

[johnbillion]

In 60404:

Application Passwords: Correct the schema of the app_id property of the application passwords REST API endpoint.

This property can contain either a UUID or an empty string.

Props sukhendu2002, johnbillion.

Fixes #53692

A late note on this – it changed the behaviour of the Application Password registration and update endpoints – they no longer accept app_id: null. This is a sensible change – you should omit the parameter to reflect your intention. Documenting the change here for future reference.

#!/bin/bash

# Bug: WordPress 6.9-RC3 rejects `app_id: null` in application-passwords endpoint
# This worked in previous versions.

# Replace these with your test credentials
USER="test@example.com"
PASSWORD="password"
SITE_URL="http://localhost/"

echo "=== Test 1: app_id omitted (works) ==="
curl -s --user "$USER:$PASSWORD" \
  -H "Content-Type: application/json" \
  -d '{"name": "test_omitted"}' \
  "$SITE_URL/wp-json/wp/v2/users/1/application-passwords" | jq .

echo ""
echo "=== Test 2: app_id: null (FAILS in 6.9-RC3) ==="
curl -s --user "$USER:$PASSWORD" \
  -H "Content-Type: application/json" \
  -d '{"app_id": null, "name": "test_null"}' \
  "$SITE_URL/wp-json/wp/v2/users/1/application-passwords" | jq .

echo ""
echo "=== Test 3: app_id: \"\" empty string (works) ==="
curl -s --user "$USER:$PASSWORD" \
  -H "Content-Type: application/json" \
  -d '{"app_id": "", "name": "test_empty"}' \
  "$SITE_URL/wp-json/wp/v2/users/1/application-passwords" | jq .

echo ""
echo "=== Test 4: app_id: valid UUID (works) ==="
curl -s --user "$USER:$PASSWORD" \
  -H "Content-Type: application/json" \
  -d '{"app_id": "550e8400-e29b-41d4-a716-446655440000", "name": "test_uuid"}' \
  "$SITE_URL/wp-json/wp/v2/users/1/application-passwords" | jq .