After implementing CallHTTP task, the next step is to consider [input](https://github.com/serverlessworkflow/specification/blob/main/dsl-reference.md#input), [output](https://github.com/serverlessworkflow/specification/blob/main/dsl-reference.md#output) and [export](https://github.com/serverlessworkflow/specification/blob/main/dsl-reference.md#export) properties
