How to specify that at least one of a group of parameters is necessary

CWL Questions
1

I am working on a CommandLineTool for nextclade. This tool can produce a number of outputs and while each one of the 5 possible outputs is optional, at least one of the options should be selected (otherwise there is not much point running the tool). Is there a way to express this in CWL?

Here is the set of parameters for which at least one needs to be chosen:

  output_json_filename:
    type: string?
    doc: Filename of output JSON results file
    inputBinding:
      prefix: --output-json
  output_csv_filename:
    type: string?
    doc: Filename of output CSV results file
    inputBinding:
      prefix: --output-csv
  output_tsv_filename:
    type: string?
    doc: Filename of output TSV results file
    inputBinding:
      prefix: --output-tsv
  output_tsv_clades_only_filename:
    type: string?
    doc: Filename to output CSV clades-only file
    inputBinding:
      prefix: --output-tsv-clades-only
  output_tree_filename:
    type: string?
    doc: Filename of output Auspice v2 tree file
    inputBinding:
      prefix: --output-tree
2

I’ve solved this like this, where an output_options record is required but all the fields are (individually) optional.

  output_options:
    type:
      type: record
      name: output_options_record
      fields:
        output_json_filename:
          type: string?
          doc: Filename of output JSON results file
          inputBinding:
            prefix: --output-json
        output_csv_filename:
          type: string?
          doc: Filename of output CSV results file
          inputBinding:
            prefix: --output-csv
        output_tsv_filename:
          type: string?
          doc: Filename of output TSV results file
          inputBinding:
            prefix: --output-tsv
        output_tsv_clades_only_filename:
          type: string?
          doc: Filename to output CSV clades-only file
          inputBinding:
            prefix: --output-tsv-clades-only
        output_tree_filename:
          type: string?
          doc: Filename of output Auspice v2 tree file
          inputBinding:
            prefix: --output-tree