code: public function chargeParams()
      {
          // Build the charge array
          $chargeDetails = [
              'name'          => $this->plan->name,
              'price'         => $this->plan->price,
              'test'          => $this->plan->isTest(),
              'trial_days'    => $this->plan->hasTrial() ? $this->plan->trial_days : 0,
              'return_url'    => URL::secure(Config::get('shopify-app.billing_redirect'), ['plan_id' => $this->plan->id]),
          ];
  
          // Handle capped amounts for UsageCharge API
          if (isset($this->plan->capped_amount) && $this->plan->capped_amount > 0) {
              $chargeDetails['capped_amount'] = $this->plan->capped_amount;
              $chargeDetails['terms'] = $this->plan->terms;
          }
  
          return $chargeDetails;
      }
docs: Returns the charge params sent with the post request.
  
  @return array