Why can't my NFS client see nested mounts on the NFS share?

Issue

• NFS server shares out filesystem with nested mount:

  [root@nfsserver ~]# cat /etc/exports 
  /nfsshare *(rw,sync)
  
  [root@nfsserver ~]# ls -laR /nfsshare/
  /nfsshare/:
  total 12
  drwxr-xr-x   3 root root 4096 Apr  1 15:56 .
  dr-xr-xr-x. 28 root root 4096 Apr  1 15:07 ..
  drwxr-xr-x.  3 root root 4096 Apr  1 15:57 nested_mount
  
  /nfsshare/nested_mount:
  total 24
  drwxr-xr-x. 3 root root  4096 Apr  1 15:57 .
  drwxr-xr-x  3 root root  4096 Apr  1 15:56 ..
  -rw-r--r--  1 root root     0 Apr  1 15:57 HelloWorld.c
  
  [root@nfsserver ~]# mount | grep nested_mount
  /dev/mapper/VolGroup01-LogVol01 on /nfsshare/nested_mount type ext4 (rw)
  

• After mounting exported share on NFS client, client doesn't see what's on nested mount:

  [root@nfsclient /]# ls -l /nfsshare/nested_mount/
  total 0