A payload which defines the inclusion set of other messages in the Tangle.
### essence(): [MilestonePayloadEssence](#milestonepayloadessence)
Returns the essence of a `MilestonePayload`.
### signatures(): [MilestoneSignature[]](#milestonesignature)
Returns the signatures of a `MilestonePayload`.
### validate(applicable_public_keys, min_threshold): void
Semantically validate a `MilestonePayload`.
| Parameter | Type | Description |
| --------------- | -------- | -------- |
| applicable_public_keys | String[] | The public keys to use to validate |
| min_threshold | long | THe minimum threshold for this to succeed (0...100) |
### id(): String
Computes the identifier of a `MilestonePayload`.