src/XdrModel/Operation/SetOptionsOp.php
public function setAuthRequired($isRequired)
    {
        if ($isRequired) {
            $this->setFlags   = $this->setFlags | static::FLAG_AUTH_REQUIRED;
            $this->clearFlags = $this->clearFlags & ~(static::FLAG_AUTH_REQUIRED);
        }
        else {
            $this->setFlags   = $this->setFlags & ~(static::FLAG_AUTH_REQUIRED);
            $this->clearFlags = $this->clearFlags | static::FLAG_AUTH_REQUIRED;
        }

        return $this;
    }
public function setAuthRequired($isRequired)
    {
        if ($isRequired) {
            $this->setFlags   = $this->setFlags | static::FLAG_AUTH_REQUIRED;
            $this->clearFlags = $this->clearFlags & ~(static::FLAG_AUTH_REQUIRED);
        }
        else {
            $this->setFlags   = $this->setFlags & ~(static::FLAG_AUTH_REQUIRED);
            $this->clearFlags = $this->clearFlags | static::FLAG_AUTH_REQUIRED;
        }

        return $this;
    }
If set, TrustLines are created with authorized set to false requiring the issuer to set it for each TrustLine

@param $isRequired
@return SetOptionsOp