code: public function pointer(string $key, string $prefix = ''): string
      {
          $prefix = rtrim($prefix, '/');
  
          if ('type' === $key) {
              return $prefix . '/type';
          }
  
          if ('id' === $key) {
              return $prefix . '/id';
          }
  
          $parts = collect(explode('.', $key));
          $field = $parts->first();
  
          if ($this->isAttribute($field)) {
              return $prefix . '/attributes/' . $parts->implode('/');
          }
  
          if ($this->isRelationship($field)) {
              $name = 1 < $parts->count() ? $field . '/' . $parts->put(0, 'data')->implode('/') : $field;
              return $prefix . "/relationships/{$name}";
          }
  
          return $prefix ? $prefix : '/';
      }
docs: Convert a validation key to a JSON pointer.
  
  @param string $key
  @param string $prefix
  @return string