WebServiceBeforeOperationRule — Child call must use parent response ($response.CostCenter$), but child response is empty

@henriqueoliveiraIAM -Please find the response below -

  1. Is parent $response data guaranteed to be available in a child call’s BeforeOperation rule?
    I don’t think that’s possible.
  2. If not, what’s the supported way to pass the parent value into the child request (e.g., staged variable, connectorStateMap, different rule stage)?
    My suggestion would be using connectorStateMap.
  3. Is requestEndPoint.setFullUrl(...) the correct approach at this stage, or should we prefer setContextUrl(...) for child calls?
    It depends, How you want to handle. In general, setContextUrl - Sets the context URL for the particular operation (Create User, Update User, Account Aggregation, etc.).e.g. - /request/getAccount
    setFullUrl - Sets the complete URL (endpoint ) of the operation that need to be performed for the particular operation (Create User, Update User, Account Aggregation, etc.).e.g. https://example.com/request/getAccount

Hope this helps.