[G1]Why run Full GC at System.gc() call?

[Manavjeet Singh]

Hi!
I was trying to understand what happens when System.gc() is called from a
java application with G1 as the garbage collector. I understood
G1CollectedHeap::collect() is called and then
G1CollectedHeap::try_collect().
But going through the code of G1CollectedHeap::try_collect() and using the
"-verbose" flag while running the java application, I realised only a full
GC will always be scheduled.
Can you please help me understand this design decision or if I am wrong in
understanding it.
Thanks!
Manavjeet Singh