Support OpenJDK in order to use -ea versions

[gortiz]

Description:
As we know, OpenJDK used to be the place where free JRE and JDKs were downloaded from, but in the new model consumers should use other vendors like temurin, microsoft, etc. This is true for all versions but the EA, which are not packaged by these vendors and therefore they should be downloaded from OpenJDK*.

As said in OpenJDK docker page:

This image is officially deprecated and all users are recommended to find and use suitable replacements ASAP. Some examples of other Official Image alternatives (listed in alphabetical order with no intentional or implied preference):

<list of publishers>

The only tags which will continue to receive updates beyond July 2022 will be Early Access builds (which are sourced from jdk.java.net), as those are not published/supported by any of the above projects.

• This is not 100% correct. Some vendors like Azul do offer EA versions in their webpage, but they are not included in the endpoint this action calls.

Justification:
In order to support newest JVMs as fast as possible, it is very useful to be able to compile and test libraries and applications using the JDK that is being development. This is specially important in a moment like this when the release in EA is going to be LTS and will include tons of improvements and new features compared to the last LTS.

[IvanZosimov]

Hi, @gortiz 👋 Thanks for the feature request! We will think about it and let you know if it's approved to be implemented or not.

[BohdanM-AVISPL]

Hello, I am wondering why there are no support of OpenJDK at all, not even Early Access? It seems to have proper license -- GPL+classpath extension.

[sormuras]

As an alternative, you're invited to use https://github.com/oracle-actions/setup-java to install Early Access releases of the JDK:

steps:
  - name: 'Set up latest JDK EA from jdk.java.net'
    uses: oracle-actions/setup-java@v1
    with:
      website: jdk.java.net
      release: EA

Note that oracle-actions/setup-java does use actions/setup-java to perform the actual installation and configuration.

Related discussion: #69