402 stands for Authentication Failed. In other words, the credentials (username / password) provided in the request are not valid. The details tab in the Gateway Audit Events log will identify the service that the request was submitted to (/foo/bar in this example).

Node           : Gateway1
Time           : 20190222 03:10:51.459
Severity       : WARNING
Request Id     : 123456789123456789
Message        : Message was not processed: Authentication Failed (402)
Audit Record ID: df564fd1va658aav6avdf4d5fds5fsdf4

Event Type     : Message Summary
Client IP      : 1.2.3.4
Service        : fooBarService [/foo/bar]
Operation      : getID
Rqst Length    : <Not Saved>
Resp Length    : <Not Saved>
Resp Status    : 0
Resp Time      : 0ms
User ID        : <No ID>
User Name      : null

The request tab may identify the username that was used in the request (john.doe in this example).

<UserId>john.doe</UserId>

Sometimes, the response tab will identify that the credentials are invalid.

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Body>
        <soapenv:Fault>
            <faultcode>soapenv:Client.InvalidCredentials</faultcode>
            <faultstring>Resubmit using the correct credentials</faultstring>
            <detail>A problem occured processing the request</detail>
        </soapenv:Fault>
    </soapenv:Body>
</soapenv:Envelope>