When attempting to join any online server in 1.12.2 and 18w05a with openjdk-10-ea+42_osx-x64_bin (downloaded from https://download.java.net/java/jdk10/archive/42/GPL/openjdk-10-ea+42_osx-x64_bin.tar.gz), Minecraft will throw "Failed to log in: The authentication servers are down for maintenance"
Mac OS X 10.11.2
OpenJDK JRE 10 (ea+42)
openjdk version "10-ea" 2018-03-20
OpenJDK Runtime Environment 18.3 (build 10-ea+42)
OpenJDK 64-Bit Server VM 18.3 (build 10-ea+42, mixed mode)
MacBookPro 12,1
java ln -s (ed) to /usr/local/bin/java10
Also tested with non-symlinked java
I'll leave this report open, but please note that Minecraft does not support Java 9 yet as it requires some major code rewrites. Please use Java 8 to play Minecraft in the meantime.