http://dl.google.com uses weak digest algorithm (SHA1)

After installing Google-Chrome, running sudo apt update, the following error is produced:

All packages are up to date.

W: http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
W: http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 3B068FB4789ABE4AEFA3BB491397BC53640DB551 uses weak digest algorithm (SHA1)

Is this a bug?

Description: Ubuntu 16.04 LTS
Release: 16.04

google-chrome-stable:
  Installed: 50.0.2661.94-1
  Candidate: 50.0.2661.94-1
  Version table:
 *** 50.0.2661.94-1 500
        500 http://dl.google.com/linux/chrome/deb stable/main amd64 Packages
        100 /var/lib/dpkg/status