Currently, the IOperationExecutor is an internal interface, but it looks very valuable if one looks to customize the part between the "logic" and "network" parts of the driver. I ask you to consider making the interface public and allow it's decoration in the fashion alike to how the cluster builder allows customization of cluster internals. Since this is an internal -> public interface extension, I don't think it will break existing code. Also, the referenced types are already public, so I presume it would not require other changes.
I understand that by exposing more of the internal implementation details you close some future paths over which the code might evolve due to requirement to contain backwards compatibility, but this interface looks like the best place to perform certain operation transformations.