Ubunto Setup failes

Ask for help.
When I try to run the ‘sudo apt-get install openjdk-8-jdk-headless’ to setup the Ubunto PhantomBot Version on a Google Cloud Platform Server I always get the following problem:

Reading package lists… Done
Building dependency tree
Reading state information… Done
Package openjdk-8-jdk-headless is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package ‘openjdk-8-jdk-headless’ has no installation candidate

And I get stuck.
I have already reinstalled the VM-instance but always the same result.

Many thanks in advance!

You dont need to install Java anymore cause Phantombot ships with its own Version of Java now.