diff --git a/lib/Event.php b/lib/Event.php
index ca394a19c..5804d21de 100644
--- a/lib/Event.php
+++ b/lib/Event.php
@@ -228,6 +228,11 @@ class Event extends ApiResource
     const SUBSCRIPTION_SCHEDULE_UPDATED = 'subscription_schedule.updated';
     const TAX_RATE_CREATED = 'tax_rate.created';
     const TAX_RATE_UPDATED = 'tax_rate.updated';
+    const TEST_HELPERS_TEST_CLOCK_ADVANCING = 'test_helpers.test_clock.advancing';
+    const TEST_HELPERS_TEST_CLOCK_CREATED = 'test_helpers.test_clock.created';
+    const TEST_HELPERS_TEST_CLOCK_DELETED = 'test_helpers.test_clock.deleted';
+    const TEST_HELPERS_TEST_CLOCK_INTERNAL_FAILURE = 'test_helpers.test_clock.internal_failure';
+    const TEST_HELPERS_TEST_CLOCK_READY = 'test_helpers.test_clock.ready';
     const TOPUP_CANCELED = 'topup.canceled';
     const TOPUP_CREATED = 'topup.created';
     const TOPUP_FAILED = 'topup.failed';
diff --git a/lib/Refund.php b/lib/Refund.php
index e452653e2..f8bfae6e4 100644
--- a/lib/Refund.php
+++ b/lib/Refund.php
@@ -57,4 +57,21 @@ class Refund extends ApiResource
      * @deprecated use FAILURE_REASON_EXPIRED_OR_CANCELED_CARD instead
      */
     const FAILURE_REASON = 'expired_or_canceled_card';
+
+    /**
+     * @param null|array $params
+     * @param null|array|string $opts
+     *
+     * @throws \Stripe\Exception\ApiErrorException if the request fails
+     *
+     * @return \Stripe\Refund the canceled refund
+     */
+    public function cancel($params = null, $opts = null)
+    {
+        $url = $this->instanceUrl() . '/cancel';
+        list($response, $opts) = $this->_request('post', $url, $params, $opts);
+        $this->refreshFrom($response, $opts);
+
+        return $this;
+    }
 }
diff --git a/lib/SKU.php b/lib/SKU.php
index 16e42b1e1..09d6c85e5 100644
--- a/lib/SKU.php
+++ b/lib/SKU.php
@@ -14,9 +14,6 @@
  *
  * Can also be used to manage inventory.
  *
- * Related guide: <a href="https://stripe.com/docs/orders-legacy">Tax, Shipping,
- * and Inventory</a>.
- *
  * @property string $id Unique identifier for the object.
  * @property string $object String representing the object's type. Objects of the same type share the same value.
  * @property bool $active Whether the SKU is available for purchase.
diff --git a/lib/Service/RefundService.php b/lib/Service/RefundService.php
index cfbef54c5..772c0f6e3 100644
--- a/lib/Service/RefundService.php
+++ b/lib/Service/RefundService.php
@@ -24,6 +24,25 @@ public function all($params = null, $opts = null)
         return $this->requestCollection('get', '/v1/refunds', $params, $opts);
     }
 
+    /**
+     * Cancels a refund with a status of <code>requires_action</code>.
+     *
+     * Refunds in other states cannot be canceled, and only refunds for payment methods
+     * that require customer action will enter the <code>requires_action</code> state.
+     *
+     * @param string $id
+     * @param null|array $params
+     * @param null|array|\Stripe\Util\RequestOptions $opts
+     *
+     * @throws \Stripe\Exception\ApiErrorException if the request fails
+     *
+     * @return \Stripe\Refund
+     */
+    public function cancel($id, $params = null, $opts = null)
+    {
+        return $this->request('post', $this->buildPath('/v1/refunds/%s/cancel', $id), $params, $opts);
+    }
+
     /**
      * Create a refund.
      *
diff --git a/lib/TaxId.php b/lib/TaxId.php
index b9ab44ac2..0d9e7e7a5 100644
--- a/lib/TaxId.php
+++ b/lib/TaxId.php
@@ -18,7 +18,7 @@
  * @property int $created Time at which the object was created. Measured in seconds since the Unix epoch.
  * @property null|string|\Stripe\Customer $customer ID of the customer.
  * @property bool $livemode Has the value <code>true</code> if the object exists in live mode or the value <code>false</code> if the object exists in test mode.
- * @property string $type Type of the tax ID, one of <code>ae_trn</code>, <code>au_abn</code>, <code>au_arn</code>, <code>br_cnpj</code>, <code>br_cpf</code>, <code>ca_bn</code>, <code>ca_gst_hst</code>, <code>ca_pst_bc</code>, <code>ca_pst_mb</code>, <code>ca_pst_sk</code>, <code>ca_qst</code>, <code>ch_vat</code>, <code>cl_tin</code>, <code>es_cif</code>, <code>eu_vat</code>, <code>gb_vat</code>, <code>ge_vat</code>, <code>hk_br</code>, <code>id_npwp</code>, <code>il_vat</code>, <code>in_gst</code>, <code>is_vat</code>, <code>jp_cn</code>, <code>jp_rn</code>, <code>kr_brn</code>, <code>li_uid</code>, <code>mx_rfc</code>, <code>my_frp</code>, <code>my_itn</code>, <code>my_sst</code>, <code>no_vat</code>, <code>nz_gst</code>, <code>ru_inn</code>, <code>ru_kpp</code>, <code>sa_vat</code>, <code>sg_gst</code>, <code>sg_uen</code>, <code>th_vat</code>, <code>tw_vat</code>, <code>ua_vat</code>, <code>us_ein</code>, or <code>za_vat</code>. Note that some legacy tax IDs have type <code>unknown</code>
+ * @property string $type Type of the tax ID, one of <code>ae_trn</code>, <code>au_abn</code>, <code>au_arn</code>, <code>bg_uic</code>, <code>br_cnpj</code>, <code>br_cpf</code>, <code>ca_bn</code>, <code>ca_gst_hst</code>, <code>ca_pst_bc</code>, <code>ca_pst_mb</code>, <code>ca_pst_sk</code>, <code>ca_qst</code>, <code>ch_vat</code>, <code>cl_tin</code>, <code>es_cif</code>, <code>eu_vat</code>, <code>gb_vat</code>, <code>ge_vat</code>, <code>hk_br</code>, <code>hu_tin</code>, <code>id_npwp</code>, <code>il_vat</code>, <code>in_gst</code>, <code>is_vat</code>, <code>jp_cn</code>, <code>jp_rn</code>, <code>kr_brn</code>, <code>li_uid</code>, <code>mx_rfc</code>, <code>my_frp</code>, <code>my_itn</code>, <code>my_sst</code>, <code>no_vat</code>, <code>nz_gst</code>, <code>ru_inn</code>, <code>ru_kpp</code>, <code>sa_vat</code>, <code>sg_gst</code>, <code>sg_uen</code>, <code>si_tin</code>, <code>th_vat</code>, <code>tw_vat</code>, <code>ua_vat</code>, <code>us_ein</code>, or <code>za_vat</code>. Note that some legacy tax IDs have type <code>unknown</code>
  * @property string $value Value of the tax ID.
  * @property null|\Stripe\StripeObject $verification Tax ID verification information.
  */
@@ -31,6 +31,7 @@ class TaxId extends ApiResource
     const TYPE_AE_TRN = 'ae_trn';
     const TYPE_AU_ABN = 'au_abn';
     const TYPE_AU_ARN = 'au_arn';
+    const TYPE_BG_UIC = 'bg_uic';
     const TYPE_BR_CNPJ = 'br_cnpj';
     const TYPE_BR_CPF = 'br_cpf';
     const TYPE_CA_BN = 'ca_bn';
@@ -46,6 +47,7 @@ class TaxId extends ApiResource
     const TYPE_GB_VAT = 'gb_vat';
     const TYPE_GE_VAT = 'ge_vat';
     const TYPE_HK_BR = 'hk_br';
+    const TYPE_HU_TIN = 'hu_tin';
     const TYPE_ID_NPWP = 'id_npwp';
     const TYPE_IL_VAT = 'il_vat';
     const TYPE_IN_GST = 'in_gst';
@@ -65,6 +67,7 @@ class TaxId extends ApiResource
     const TYPE_SA_VAT = 'sa_vat';
     const TYPE_SG_GST = 'sg_gst';
     const TYPE_SG_UEN = 'sg_uen';
+    const TYPE_SI_TIN = 'si_tin';
     const TYPE_TH_VAT = 'th_vat';
     const TYPE_TW_VAT = 'tw_vat';
     const TYPE_UA_VAT = 'ua_vat';