the Contract is composed of :
the short name of the initiator
the resources to negotiate
a delay to answer
a default answer
a string representation of resources
the identificator of the contract
the ContractProperties is composed of :
the id of the related contract
the list of participants
the minimum number of agreements needed to confirm the contract
the number of agreements obtained
the maximum number of modification request
the number of times the Contract has been modified
the maximum number of renegotiations
the number of renegotiations done
It will only be used by a Goal.