Inconsistent job outputs representation

[fmigneault]

Describe the bug

When requesting GET [...]/jobs/{jobID}/inputs, the returned contents provide the originally submitted outputs (transmissionMode, format, etc.) to help debug a potential job failure or interpret the obtained result structure, formats, media-types, etc.

However, to support outputs filtering (#380), the outputs: {} definition must be used to indicate no outputs at all. Currently, whether omitting outputs or explicitly indicating an empty mapping results in the Job Inputs endpoint to return outputs: {}, possibly leading to confusing interpretation.

Expected behavior

Omitting outputs: {} from the job execution request should lead to outputs: null (explicitly indicated in the JSON) to distinguish it from an actual outputs: {}.

Context

• Relates to Filter out non-requested outputs #380
• Relates to job execution results #713