Model/Api.php
public function upsertAclItem($aclId, $itemValue, $negated, $comment = 'Added by Magento Module', $subnet = false)
    {
        $body = [
            'ip' => $itemValue,
            'negated' => $negated,
            'comment' => $comment
        ];

        if ($subnet) {
            $body['subnet'] = $subnet;
        }

        $url = $this->_getApiServiceUri(). 'acl/'. $aclId . '/entry';
        $result = $this->_fetch($url, \Zend_Http_Client::POST, $body);

        return $result;
    }
public function upsertAclItem($aclId, $itemValue, $negated, $comment = 'Added by Magento Module', $subnet = false)
    {
        $body = [
            'ip' => $itemValue,
            'negated' => $negated,
            'comment' => $comment
        ];

        if ($subnet) {
            $body['subnet'] = $subnet;
        }

        $url = $this->_getApiServiceUri(). 'acl/'. $aclId . '/entry';
        $result = $this->_fetch($url, \Zend_Http_Client::POST, $body);

        return $result;
    }
Upsert single ACL entry

@param $aclId
@param $itemValue
@param $negated
@param string $comment
@param bool $subnet
@return bool|mixed
@throws LocalizedException