message: add role assignment
diff: },
  {
  "$ref": "#/definitions/StepArmDeploymentScript"
  + },
  + {
  + "$ref": "#/definitions/StepRoleAssignment"
  }
  ]
  },
  ],
  "additionalProperties": false
  },
  + "StepRoleAssignment": {
  + "type": "object",
  + "allOf": [
  + {
  + "$ref": "#/definitions/StepBase"
  + }
  + ],
  + "properties": {
  + "roleAssignment": {
  + "type": "object",
  + "properties": {
  + "roleName": {
  + "type": "string"
  + },
  + "roleDefinitionId": {
  + "type": "string"
  + },
  + "principalId": {
  + "type": "string"
  + },
  + "scope": {
  + "type": "string"
  + },
  + "principalType": {
  + "type": "string",
  + "enum": ["User", "Group", "ServicePrincipal", "ForeignGroup", "Device"],
  + "default": "ServicePrincipal"
  + }
  + },
  + "oneOf": [
  + {
  + "required": ["roleName", "principalId", "scope"]
  + },
  + {
  + "required": ["roleDefinitionId", "principalId", "scope"]
  + }
  + ]
  + },
  + "step": {},
  + "description": {},
  + "variables": {}
  + },
  + "required": ["roleAssignment"],
  + "additionalProperties": false
  + },
  "JsonPatchOp": {
  "type": "object",
  "description": "Change a JSON document in a format described by RFC 6902",
  