ContractNegotiationEventMessageSchema
@typestringrequired
Example: 
ContractNegotiationEventMessageconsumerPidstringrequired
Example: 
urn:example:consumerPidproviderPidstringrequired
Example: 
urn:example:providerPideventTypestringrequired
Example: 
NEGOTIATION_STARTEDContractNegotiationEventMessageSchema
{
  "@type": "ContractNegotiationEventMessage",
  "consumerPid": "urn:example:consumerPid",
  "providerPid": "urn:example:providerPid",
  "eventType": "NEGOTIATION_STARTED"
}