FDP_Value will contain an empty string.
You can try JSONPath here: http://jsonpath.com/

Inputs
Input Name | Input Code | Required | Description |
|---|---|---|---|
JSONSource |
| Yes | JSONSource to parse |
JSONPathExpression |
| Yes | The JSONPathexpression to use to find a value in the JSONSource |
Require non-blank Output |
| No | If checked, the output must be non-blank at the end of execution or the execution will fail. @Since 9.0.0.7 |
Outputs
Output Name | Required | Description |
|---|---|---|
| No | The value returned from the JSONPath expression is returned to the workflow in this variable. |