Function resolve_config 

pub fn resolve_config(
    config: &Value,
    instance_config: &Value,
    instance_metadata: &Value,
    event_payload: Option<&Value>,
) -> Result<Value, TemplateError>

Resolve every $config. / $instance. / $event. string in config against the running instance. Non-template strings and non-string scalars pass through unchanged; arrays and objects are walked recursively.