Tested 1.0.0-0ubuntu4~18.10.0 on Cosmic:

ubuntu@ip-172-31-11-18:~$ sudo apt install --reinstall ec2-hibinit-agent
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded.
Need to get 0 B/10.0 kB of archives.
After this operation, 0 B of additional disk space will be used.
debconf: delaying package configuration, since apt-utils is not installed
(Reading database ... 66281 files and directories currently installed.)
Preparing to unpack .../ec2-hibinit-agent_1.0.0-0ubuntu4~18.10.0_all.deb ...
Unpacking ec2-hibinit-agent (1.0.0-0ubuntu4~18.10.0) over (1.0.0-0ubuntu4~18.10.0) ...
Setting up ec2-hibinit-agent (1.0.0-0ubuntu4~18.10.0) ...
ubuntu@ip-172-31-11-18:~$ service hibinit-agent status
● hibinit-agent.service - EC2 instance hibernation setup agent
   Loaded: loaded (/lib/systemd/system/hibinit-agent.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Tue 2019-03-12 14:24:20 UTC; 31s ago
     Docs: file:/usr/share/doc/ec2-hibinit-agent/README

Mar 12 14:24:20 ip-172-31-11-18 /hibinit-agent[2972]: Running: swapoff /swap-hibinit
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Effective config: {'log_to_syslog': True, 'log_to_stderr': True, 'mkswap': 'mkswap {swapfile}', 'swapon': 'swapon {swapfi
le}', 'swapoff': 'swapoff {swapfile}', 'touch_swap': False, 'grub_update': True, 'swap_percentage': 100, 'swap_mb': 4000}
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Will check if swap is at least: 4000 megabytes
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: There's sufficient swap available (have 4194304000, need 4194304000)
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Running: swapon /swap-hibinit
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Updating the kernel offset for the swapfile: /swap-hibinit
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Setting swap device to 51713 with offset 245760
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Done updating the swap offset. Turning swapoff
Mar 12 14:24:20 ip-172-31-11-18 hibinit-agent[2972]: Running: swapoff /swap-hibinit
Mar 12 14:24:20 ip-172-31-11-18 systemd[1]: Started EC2 instance hibernation setup agent.
ubuntu@ip-172-31-11-18:~$ sudo apt purge ec2-hibinit-agent
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  ec2-hibinit-agent*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 59.4 kB disk space will be freed.
Do you want to continue? [Y/n] 
(Reading database ... 66281 files and directories currently installed.)
Removing ec2-hibinit-agent (1.0.0-0ubuntu4~18.10.0) ...
(Reading database ... 66268 files and directories currently installed.)
Purging configuration files for ec2-hibinit-agent (1.0.0-0ubuntu4~18.10.0) ...
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/40-force-partuuid.cfg'
Sourcing file `/etc/default/grub.d/50-cloudimg-settings.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.18.0-1011-aws
Found initrd image: /boot/initrd.img-4.18.0-1011-aws
Found linux image: /boot/vmlinuz-4.18.0-1008-aws
Found initrd image: /boot/initrd.img-4.18.0-1008-aws
done
ubuntu@ip-172-31-11-18:~$ ls -alh /etc/default/grub.d/
total 16K
drwxr-xr-x 2 root root 4.0K Mar 12 14:25 .
drwxr-xr-x 3 root root 4.0K Mar 12 11:51 ..
-rw-r--r-- 1 root root   32 Feb 12 18:40 40-force-partuuid.cfg
-rw-r--r-- 1 root root  434 Feb 12 18:45 50-cloudimg-settings.cfg
ubuntu@ip-172-31-11-18:~$ ls /
bin  boot  dev  etc  home  initrd.img  initrd.img.old  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  snap  srv  sys  tmp  usr  var  vmlinuz  vmlinuz.old
ubuntu@ip-172-31-11-18:~$ grep resume /boot/grub/grub.cfg 
ubuntu@ip-172-31-11-18:~$ 

The first hibernation/resume cycle succeeded, but the second failed. The failure seems do be due to a kernel issue since the ACPI events are not seen after the resume.

Since the package seems to be working well I'm marking the verification as successful.