autotask share is null 12cR2 - resource manager - what does that mean?

hi,

autotask share is null yet it has utilization limit of 90 and parallel_server_limit 100. Anyone knows what that means?

what if default directive is null?

according to reference null is -1 which is 20%, does that make sense? Why not just show -1?

What if I set default directive to null, would that also make it 20%?

https://docs.oracle.com/database/121/ARPLS/d_resmgr.htm#ARPLS73833

thank you

SELECT plan,

       pluggable_database,

       shares,

       utilization_limit AS util,

       parallel_server_limit AS parallel

FROM   dba_cdb_rsrc_plan_directives

WHERE  plan = 'TEST_CDB_PLAN'

ORDER BY pluggable_database;

this is common occurrence everywhere