Update documentation about supported Java and Tomcat versions

[offtherailz]

Description

Actually MapStore build process uses Java 8.
Anyway the documentation tells to use java 8 only as a minimal version.

Here a user notified a failure building with Java 16 (confirmed my me, @offtherailz)
I did also a test of build with Java 13. The build is successful.

We have to investigate the issue notified in Java 16 and define more the Java versions supported by MapStore, or fix the problem with Java 16, if possible.

Also adding the information about the suggested tomcat version should be added

Documentation section involved

• User Guide
• Developer Guide

Other useful information

[offtherailz]

We tested with @randomorder
The version working on Ubuntu 20.04 :

• tomcat 9.0.31
• JDK 11

[mbarto]

We should at least have:

• a list of tested JRE versions, that we know are working
• a list of tested Tomcat versions, that we know are working and the related minimum required java version

To collect these lists we need to install various versions of JRE and tomcats and a set of smoke-tests for the backend functionalities:

• geostore (home page resources load / modify)
• security (login / logout)
• datadir configs/ assets loading
• extensions uploading

[offtherailz]

Just to reduce the list here a small summary of my thoughts

Starting from this table about Java Version Support (source)

Java SE 7 | July 2011 | April 2015 | July 2022

Java SE 8 (LTS)	March 2014	January 2019 for Oracle (commercial)December 2030 for Oracle (non-commercial)December 2030 for ZuluAt least May 2026 for AdoptOpenJDKAt least May 2026 for Amazon Corretto	December 2030
Java SE 9	September 2017	March 2018 for OpenJDK	N/A
Java SE 10	March 2018	September 2018 for OpenJDK	N/A
Java SE 11 (LTS)	September 2018	September 2027 for ZuluAt least October 2024 for AdoptOpenJDKAt least September 2027 for Amazon Corretto	September 2026,or September 2027 for Zulu,[8] e.g.
Java SE 12	March 2019	September 2019 for OpenJDK	N/A
Java SE 13	September 2019	March 2020 for OpenJDK	N/A
Java SE 14	March 2020	September 2020 for OpenJDK	N/A
Java SE 15	September 2020	March 2021 for OpenJDK, March 2023 for Zulu[8]	N/A
Java SE 16	March 2021	September 2021 for OpenJDK	N/A
Java SE 17 (LTS)	September 2021	September 2030 for Zulu	TBA
Java SE 18	March 2022	September 2022 for OpenJDK	N/A

And this compatibility table for Tomcat (source)

Servlet Spec	JSP Spec	EL Spec	WebSocket Spec	Authentication (JASIC) Spec	Apache Tomcat Version	Latest Released Version	Supported Java Versions
5.1	TBD	TBD	TBD	TBD	10.1.x	10.1.0-M1 (alpha)	8 and later
5.0	3.0	4.0	2.0	2.0	10.0.x	10.0.7	8 and later
4.0	2.3	3.0	1.1	1.1	9.0.x	9.0.48	8 and later
3.1	2.3	3.0	1.1	1.1	8.5.x	8.5.68	7 and later
3.1	2.3	3.0	1.1	N/A	8.0.x (superseded)	8.0.53 (superseded)	7 and later
3.0	2.2	2.2	1.1	N/A	7.0.x	7.0.109	6 and later(7 and later for WebSocket)

(7 and later for WebSocket)

I think we can take in account to support Java LTS versions (also Java 16 will be discontinued in updates the end of this year):

• 8
• 11
• 17 (probably not working)

And for tomcat 8, 9, 10.

This is only an opinion, what do you think ?

[mbarto]

@offtherailz agree with both. We can eventually try to understand which version JVM made changes incompatible with our current code and evaluate if the needed changes are trivial or not