How to set client id when making a service callout to pingfederate to authorize an access token

I am trying to call Ping Federate from Apigee using certificate authentication to authorize a token that was generated by Ping Federate

I have set up Ping and both Apigee with the certificate

My service callout is below. The thing I am missing is how to set the Ping Federate client id in my service callout

<ServiceCallout async="false" continueOnError="false" enabled="true" name="Service-Callout-1">
    <DisplayName>Service Callout-1</DisplayName>
    <Properties/>
    <Request clearPayload="true" variable="myRequest">
        <Set>
            <QueryParams>
                <QueryParam name="token">{access_token}</QueryParam>
                <QueryParam name="token_type_hint">access_token</QueryParam>
            </QueryParams>
            <Verb>POST</Verb>
        </Set>
    </Request>
    <Response>pingTokenValidationResponse</Response>
    <HTTPTargetConnection>
        <Properties/>
        <URL>https://PING_FEDERATE/as/introspect.oauth2</URL>
        <SSLInfo>
            <ClientAuthEnabled>true</ClientAuthEnabled>
            <Enabled>true</Enabled>
            <KeyAlias>test</KeyAlias>
            <KeyStore>test</KeyStore>
            <TrustStore>test</TrustStore>
        </SSLInfo>
    </HTTPTargetConnection>
</ServiceCallout>