Function resolve 

pub fn resolve(
    config: &Config,
    secrets: &dyn SecretResolver,
) -> Result<Vec<ResolvedSource>, ConfigError>

Build every configured source, in name order.

The order is the map’s, so two runs over one configuration produce the same sources in the same sequence — which is what makes a multi-source result stable enough to page through.

Errors

Returns what validate_sources returns, and ConfigError::Setting naming sources.<name> when the plugin itself refuses to build the source.