Controller/Adminhtml/FastlyCdn/Edge/Dictionary/ListAll.php
public function execute()
    {
        $result = $this->resultJson->create();

        try {
            $activeVersion = $this->getRequest()->getParam('active_version');
            $dictionaries = $this->api->getDictionaries($activeVersion);

            if (is_array($dictionaries) && empty($dictionaries)) {
                return $result->setData([
                    'status'        => true,
                    'dictionaries'  => []
                ]);
            }

            if (!$dictionaries) {
                return $result->setData([
                    'status'    => false,
                    'msg'       => 'Failed to fetch dictionaries.'
                ]);
            }

            return $result->setData([
                'status'        => true,
                'dictionaries'  => $dictionaries
            ]);
        } catch (\Exception $e) {
            return $result->setData([
                'status'    => false,
                'msg'       => $e->getMessage()
            ]);
        }
    }
public function execute()
    {
        $result = $this->resultJson->create();

        try {
            $activeVersion = $this->getRequest()->getParam('active_version');
            $dictionaries = $this->api->getDictionaries($activeVersion);

            if (is_array($dictionaries) && empty($dictionaries)) {
                return $result->setData([
                    'status'        => true,
                    'dictionaries'  => []
                ]);
            }

            if (!$dictionaries) {
                return $result->setData([
                    'status'    => false,
                    'msg'       => 'Failed to fetch dictionaries.'
                ]);
            }

            return $result->setData([
                'status'        => true,
                'dictionaries'  => $dictionaries
            ]);
        } catch (\Exception $e) {
            return $result->setData([
                'status'    => false,
                'msg'       => $e->getMessage()
            ]);
        }
    }
Get all dictionaries for active version

@return $this|\Magento\Framework\App\ResponseInterface|\Magento\Framework\Controller\ResultInterface