Including child items in query param yields 400 Bad Request for workers api

Summary:

Getting a 400 Bad Request every time I include child elements in query parameter

Content (required):

Hello,

This works:

hcmRestApi/resources/latest/workers?q=PersonNumber='32560'&expand=names&onlyData=true

This does not work:

hcmRestApi/resources/latest/workers?q=names.LastName='Smith'&expand=names&onlyData=true

Error code is "URL request parameter q with value names.LastName='Smith' is not valid."

What am I doing wrong? Shouldn't I be able to query the workers api doing this? Seems like it only works if I include elements in the root for my q parameter. Every time I delve a bit deeper and include a child element it bombs out.