code: public function getFieldOptions($field)
      {
          if (!$this->hasField($field)) {
              return [];
          }
  
          if (!isset($this->fields[$field]['__options__'])) {
              $this->fields[$field]['__options__'] = $this->copyArrayValues(
                  $this->fields[$field],
                  [
                      'attributes',
                      'options',
                      'label' => 'options',
                      'required' => ['key' => ['attributes','*'], 'value' => 'required', 'if' => true],
                      'type',
                  ]
              );
          }
  
          return $this->fields[$field]['__options__'];
      }
docs: Get the field option array compatible with element spec.
  
  @param string $field
  
  @return array