Feat: Pull out maven-executor into its own project

[cstamas]

The main goal of maven-executor is ability to execute Maven 3/4 in "embedded" and "forked" mode, and has not related with Maven release lifecycle itself (and is dependency-less as well). So, let's move it out into own project.

https://github.com/apache/maven-executor

The new library executes Maven in:

• forked or embedded mode, but introduces other providers as well
• supports Maven 3 and 4
• the main maven-executor module is Java 8, dependency-less library (is MR-JAR, and on 9+ is modular and provides ToolProvider SPI integration as well)

[hboutemy]

question: what about maven-verifier and maven-invoker shared components vs maven-executor https://maven.apache.org/shared/index.html ?
if we have a third shared component, we should a t least make visible about the 3 choices, isn't it?

[cstamas]

Re site, I did not do anything, and I agree, we need visibility.

Re projects, there were some issues:
apache/maven-verifier#186
apache/maven-invoker#164

[hboutemy]

oh, if maven-executor is expected to be the replacement for maven-invoker and maven-verifier, let's make it a shared component and document it from the start, please

and I suppose there are also related issues or PRs in related plugins https://maven.apache.org/plugins/ like maven-invoker-plugin and/or maven-verifier-plugin?

[cstamas]

Yes, Maven project was inconsistent (or maybe "organic") in this respect, had wildly different projects meant to perform pretty much same thing, but there were huge differences in capabilities (fork-only vs fork-embedded) and APIs (CLI-like vs fully mimic Maven CLI).

The idea of maven-executor is to remain simple, does not stand in a way (ie. no need to release if new Maven CLI option is added) and offer fork-embed (and even more, see docker based ones) running options, without any need for "client code" to change, is just matter of configuration.

[slawekjaranowski]

😄 my old mail - https://lists.apache.org/thread/20m5llon639s2vvps4o8qm9crpb2hg8n

[cstamas]

maven-executor is now Java 8 baseline with MR-JAR version (9) for module-info and ToolProvider SPI support