Apigee X Create custom OAuthV2 access_token

[donutquan]

I am relatively new to Apigee and want to use the "apigee.access_token" generated by Apigee and append it to one of my existing variables called "tokenPayLoad". After that, I want to use this newly formed access_token for future calls to my API.

I have tried using SetOAuthV2Info policy but it still does not work as subsequent calls requiring access_token still check with the originally generated access_token.

<ProxyEndpoint name="token">
...
<Flow name="token">
    <Request>
       <Step>
          <Name>Token-BuildRequest</Name>
       </Step>
    </Request>
    <Response>
       <Step>
          <Name>GenerateAccessToken</Name>
       </Step>
       <Step>
          <Name>Token-BuildResponse</Name>
       </Step>
       <Step>
          <Name>AM-TokenResponse</Name>
       </Step>
    </Response>
</Flow>
...
<ProxyEndpoint name="verification">
...
<Flow name="verify">
    <Request>
        <Step>
            <Name>OAuthv2Verify</Name>
        </Step>
        <Step>
            <Name>RF-InvalidToken</Name>
            <Condition>error.status.code = "401"</Condition>
        </Step>
    </Request>
</Flow>

GenerateAccessToken

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<OAuthV2 async="false" continueOnError="false" enabled="true" name="GenerateAccessToken">
    <DisplayName>GenerateAccessToken</DisplayName>
    <Operation>GenerateAccessToken</Operation>
    <ExpiresIn>900000</ExpiresIn>
    <Algorithm>RS512</Algorithm>
    <GenerateResponse enabled="true"/>
    <Scope>scope</Scope>
    <SupportedGrantTypes>
        <GrantType>client_credentials</GrantType>
    </SupportedGrantTypes>
    <GrantType>grant_type</GrantType>
    <TokenType>Bearer</TokenType>
    <TokenLength>6000</TokenLength>
    </Attributes>
</OAuthV2>

TokenBuildResponse.js

var tokenPayLoad = JSON.parse(context.getVariable('tokenResponsePayload'));
const accessToken = context.getVariable('apigee.access_token');
tokenPayLoad.access_token = tokenPayLoad.access_token + "." + accessToken
context.setVariable('response.content', JSON.stringify(tokenPayLoad));

OAuth2Verify

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<OAuthV2 async="false" continueOnError="false" enabled="true" name="OAuthv2Verify">
    <DisplayName>OAuthv2Verify</DisplayName>
    <Operation>VerifyAccessToken</Operation>
    <Scope>TestApp</Scope>
    <SupportedGrantTypes/>
    <GenerateResponse enabled="true"/>
    <Tokens/>
</OAuthV2>