Processing without slice-timing correction

The EPI(fMRI) dicom data downloaded from PACS seems already slice-timing corrected (one volume per one dcm file). It can’t converted as 4D at once, but should converted to 3D Nifti first and collapsed.
How should I write the json file?
Is there any way to create json from already converted nifti file?

My mistake, slice-timing can be ignored via --ignore slicetiming option.

The remaining question is whether it is possible to create BIDS .json from nifti file