chore: remove deprecated, unused add_credit_card function

CHANGELOG.md

@@ -1,5 +1,11 @@
 # CHANGELOG
 
+## Next Release
+
+- Removes the deprecated, unusable `add_credit_card` function
+  - Stripe has disabled the ability to pass plain credit card details over the wire and now requires using [Stripe.js/Elements/Checkout](https://support.stripe.com/questions/card-tokenization-restrictions-using-publishable-keys). Follow the [Decentralized (EasyPost-Manage Billing) Guide](https://docs.easypost.com/guides/get-started-with-forge/easypost-managed-billing-guide#referralcustomer-billing-management) for more details on the new flow to use.
+  - Makes `referral_customer.retrieve_easypost_stripe_api_key` public to help facilitate adding credit cards using Stripe.js
+
 ## v7.7.0 (2026-06-25)
 
 - Adds `params` to `request_pin` ensuring users can pass `easypost_details` to the call

lib/easypost/services/referral_customer.rb

@@ -40,25 +40,6 @@ def get_next_page(collection, page_size = nil)
     all(params)
   end
 
-  # Add a credit card to EasyPost for a ReferralCustomer without needing a Stripe account. This function requires the ReferralCustomer User's API key.
-  def add_credit_card(referral_api_key, number, expiration_month, expiration_year, cvc, priority = 'primary')
-    easypost_stripe_api_key = retrieve_easypost_stripe_api_key
-
-    begin
-      stripe_credit_card_token = create_stripe_token(
-        number,
-        expiration_month,
-        expiration_year,
-        cvc,
-        easypost_stripe_api_key,
-      )
-    rescue StandardError
-      raise EasyPost::Errors::ExternalApiError.new(EasyPost::Constants::STRIPE_CARD_CREATE_FAILED)
-    end
-
-    create_easypost_credit_card(referral_api_key, stripe_credit_card_token, priority)
-  end
-
   # Add a credit card to EasyPost for a ReferralCustomer with a payment method ID from Stripe. This function requires the ReferralCustomer User's API key.
   def add_credit_card_from_stripe(referral_api_key, payment_method_id, priority = 'primary')
     params = {
@@ -94,61 +75,9 @@ def add_bank_account_from_stripe(referral_api_key, financial_connections_id, man
     EasyPost::InternalUtilities::Json.convert_json_to_object(response)
   end
 
-  private
-
   # Retrieve EasyPost's Stripe public API key.
   def retrieve_easypost_stripe_api_key
     response = @client.make_request(:get, 'partners/stripe_public_key', nil, 'beta')
     response['public_key']
   end
-
-  # Get credit card token from Stripe.
-  def create_stripe_token(number, expiration_month, expiration_year,
-                          cvc, easypost_stripe_token)
-    headers = {
-      # This Stripe endpoint only accepts URL form encoded bodies.
-      Authorization: "Bearer #{easypost_stripe_token}",
-      'Content-type': 'application/x-www-form-urlencoded',
-    }
-
-    credit_card_hash = {
-      card: {
-        number: number,
-        exp_month: expiration_month,
-        exp_year: expiration_year,
-        cvc: cvc,
-      },
-    }
-
-    form_encoded_params = EasyPost::InternalUtilities.form_encode_params(credit_card_hash)
-
-    uri = URI.parse('https://api.stripe.com/v1/tokens')
-    http = Net::HTTP.new(uri.host, uri.port)
-    http.use_ssl = true
-    request = Net::HTTP::Post.new(uri.request_uri, headers)
-    query = URI.encode_www_form(form_encoded_params)
-
-    response = http.request(request, query)
-    response_json = JSON.parse(response.body)
-    response_json['id']
-  end
-
-  # Submit Stripe credit card token to EasyPost.
-  def create_easypost_credit_card(referral_api_key, stripe_object_id, priority = 'primary')
-    wrapped_params = {
-      credit_card: {
-        stripe_object_id: stripe_object_id,
-        priority: priority,
-      },
-    }
-    referral_client = EasyPost::Client.new(api_key: referral_api_key)
-    response = referral_client.make_request(
-      :post,
-      'credit_cards',
-      wrapped_params,
-      'beta',
-    )
-
-    EasyPost::InternalUtilities::Json.convert_json_to_object(response)
-  end
 end