Failed to build - Downloading JLINE09 failed

[samtregar]

I tried following the install instructions on my Ubuntu 20.04.1 system and got this from mx build:

Error reading from http://central.maven.org/maven2/com/github/jbellis/jamm/0.3.1/jamm-0.3.1.jar: <urlopen error [Errno -3] Temporary failure in name resolution>
WARNING: ** If behind a firewall without direct internet access, use the http_proxy environment variable (e.g. "env http_proxy=proxy.company.com:80 mx ...") or download manually with a web browser.
<open file '<stderr>', mode 'w' at 0x7f70a79dd270>
Error reading from http://central.maven.org/maven2/jline/jline/0.9.94/jline-0.9.94.jar: <urlopen error [Errno -3] Temporary failure in name resolution>
WARNING: ** If behind a firewall without direct internet access, use the http_proxy environment variable (e.g. "env http_proxy=proxy.company.com:80 mx ...") or download manually with a web browser.
<open file '<stderr>', mode 'w' at 0x7f70a79dd270>
Downloading JLINE09 failed
Downloading JAMM failed
2 build tasks failed

It seems "central.maven.org" does not exist? What should I do to fix this?