ComputeHash computes contents hash based on previous hash.

------------------------------------------------------------------------------------------- DockerBuild------------------------------------------------------------------------------------------- This function allows a "pass-through" build of chaincode within a docker container as an alternative to using standard "docker build" + Dockerfile mechanisms.

HashFilesInDir computes h=hash(h,file bytes) for each file in a directoryDirectory entries are traversed recursively.

IsCodeExist checks the chaincode if exists.