Function default_gap_sync_body_policy 

pub fn default_gap_sync_body_policy(
    blocks_pruning: BlocksPruning,
) -> GapSyncBodyPolicyProvider

The default gap sync body policy provider, derived from the block pruning configuration: archive nodes backfill the whole gap with bodies, pruned nodes headers and justifications only.

Storage-chain nodes install their own provider instead, via BuildNetworkParams::gap_sync_body_policy.