[defect] Set default value to be Null for the json parameters (darkFileName, sensitivityFileName, maskFileName) in the schema.

[glass-ships]

Problem Description:

If default values are given in the schema, Null cannot be taken as an input. As a result, one cannot set Null for darkFileName, sensitivityFileName, maskFileName in the current version.
When user use Null or '' in either darkFileName, sensitivityFileName, maskFileName then the program will fall back to the default value in schema.

Steps to Reproduce:

darkFileName = “” (or Null so that we don’t want to process darkCurrent) will lead to the use of the default darkcurrent file defined in the Schema, instead of ‘no-darkcurrent correction’

The users should be able to apply empty darkFileName, sensitivityFileName, or maskFileName in reduction

Investigation/Analysis Results:

[glass-ships]

This issue was migrated from code.ornl.gov.