curl -X GET 'https://api.example.com/subjects/by-external?type=user&externalId=user-456' \
  -H 'Authorization: Bearer YOUR_TOKEN'

const axios = require('axios');

const { data } = await axios.get('https://api.example.com/subjects/by-external', {
  params: { type: 'user', externalId: 'user-456' },
  headers: { 'Authorization': 'Bearer YOUR_TOKEN' },
});

[
  {
    "id": "sub_123",
    "type": "user",
    "externalId": "user-456",
    "metadata": {}
  }
]