Updates the Handler specified by the {definitionId} parameter with the property values sent in the request body.

The properties property should be a JSON object (map) of handler property names to values.

Example

```javascript
{
  "properties": {
    "propertyName1": "updatedPropertyValue1",
    "propertyName2": "updatedPropertyValue2"
  }
}
```

NOTE All properties in the request body are optional, and only the properties supplied will be updated.