Conversion of strings with just whitespace when storing in postgres

We are moving data from old systems to a new system and noted that one entry had a tax number of " ".
Now, that is not a valid tax number, but we realized that the corresponding DB row has a value of
null
instead.
Is this the default behaviour for strings that contain only whitespace?
Is there an option to disable this behaviour and what are the caveats if we do?
Was this page helpful?