When I try to use relative path to specify for customWorkspace as described in this documatation. I found that it is not clear what is it mean in the documentation mean by "workspace root on the node". For example:

pipeline { agent { node { 
  label 'my_pc'
  customWorkspace 'hello' } }
...
}

#1 With above code, I got WORKSPACE=C:\BLD\hello

#2 When I specify customWorkspace "", I got WORKSPACE=C:\BLD\workspace\my_jenkins_job_path\my_job_name

M1 If the "workspace root on the node" was C:\BLD, #1 would understandable and #2 would not make sense .

M2 If the "workspace root on the node" was C:\BLD\workspace\my_jenkins_job_path\my_job_name, #1 would not make sense , #2 would understandable .

My personal refer M2, but both is really, really confusing to me to understand.