Interface GetTransactionTreesResponse

{
    transactions: [{
        commandId: 'some-command-id',
        effectiveAt: {
            seconds: 1554382900
            nanoseconds: 0
        },
        offset: '42',
        transactionId: 'some-tx-id',
        workflowId: 'some-workflow-id',
        eventsById: {
            'some-event-id': {
                eventType: 'created',
                eventId: 'some-event-id',
                contractId: 'some-contract-id',
                templateId: {
                    packageId: 'my-package-id',
                    moduleName: 'SomeModule',
                    entityName: 'SomeTemplate'
                },
                arguments: {
                    fields: {
                        someKey: { valueType: 'bool', bool: true }
                    }
                },
                witnessParties: [ 'Alice', 'Bob' ]
            }
        },
        rootEventIds: [
            'event-1',
            'event-2'
        ]
    }]
}

To express values in a more concise way, you can have a look at the ValueHelpers.