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

        try {
            $aclId = $this->getRequest()->getParam('acl_id');
            $value = $this->getRequest()->getParam('item_value');
            $comment = $this->getRequest()->getParam('comment_value');
            $negated = 0;

            if ($value[0] == '!') {
                $negated = 1;
                $value = ltrim($value, '!');
            }

            // Handle subnet
            $ipParts = explode('/', $value);
            $subnet = false;
            if (!empty($ipParts[1])) {
                if (is_numeric($ipParts[1]) && (int)$ipParts[1] < 129) {
                    $subnet = $ipParts[1];
                } else {
                    return $result->setData([
                        'status'    => false,
                        'msg'       => 'Invalid IP subnet format.'
                    ]);
                }
            }

            if (!filter_var($ipParts[0], FILTER_VALIDATE_IP)) {
                return $result->setData([
                    'status'    => false,
                    'msg'       => 'Invalid IP address format.'
                ]);
            }

            $createAclItem = $this->api->upsertAclItem($aclId, $ipParts[0], $negated, $comment, $subnet);

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

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

        try {
            $aclId = $this->getRequest()->getParam('acl_id');
            $value = $this->getRequest()->getParam('item_value');
            $comment = $this->getRequest()->getParam('comment_value');
            $negated = 0;

            if ($value[0] == '!') {
                $negated = 1;
                $value = ltrim($value, '!');
            }

            // Handle subnet
            $ipParts = explode('/', $value);
            $subnet = false;
            if (!empty($ipParts[1])) {
                if (is_numeric($ipParts[1]) && (int)$ipParts[1] < 129) {
                    $subnet = $ipParts[1];
                } else {
                    return $result->setData([
                        'status'    => false,
                        'msg'       => 'Invalid IP subnet format.'
                    ]);
                }
            }

            if (!filter_var($ipParts[0], FILTER_VALIDATE_IP)) {
                return $result->setData([
                    'status'    => false,
                    'msg'       => 'Invalid IP address format.'
                ]);
            }

            $createAclItem = $this->api->upsertAclItem($aclId, $ipParts[0], $negated, $comment, $subnet);

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

            return $result->setData([
                'status'        => true,
                'id'            => $createAclItem->id,
                'comment'       => $createAclItem->comment,
                'created_at'    => $createAclItem->created_at
            ]);
        } catch (\Exception $e) {
            return $result->setData([
                'status'    => false,
                'msg'       => $e->getMessage()
            ]);
        }
    }
Create ACL entry for specific ACL

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