Function sql_query_poll_source_factory 

pub fn sql_query_poll_source_factory(
    id: &str,
    config: Value,
    retry: Option<RetryPolicy>,
) -> Result<Box<dyn Source>>

Registry factory for SqlQueryPollSource. Registered by courier::registry::register_builtin under kind "sql_query_poll". The optional retry policy is extracted by the registry and threaded into the source’s PollScheduler.