Function checkpoint_input_objects 

pub fn checkpoint_input_objects(
    checkpoint: &Checkpoint,
) -> Result<BTreeMap<ObjectID, (&Object, ObjectDigest)>>

First-seen input version of every object that existed before the checkpoint and was used as an input to some transaction in it. Mirrors the helper of the same name in sui-indexer-alt-consistent-store::handlers.

Objects created or unwrapped within the checkpoint are excluded. Used by the diff-based indexes (object_by_owner etc.) to remove the rows that the prior state contributed before re-inserting the rows that the posterior state contributes.