Look at JaCoCo for IdP V4

The good news is that the EclEmma plugin for Eclipse is now based on JaCoCo and most people in the 2020-08-21 dev call were happy that they can use this to get what they needed if they have the time and inclination.

The explicit use of JaCoCo would give us a number of other facilities (graphics in Jenkins jobs, failing Jenkins jobs under specific criteria, detailed reporting) but while these seem like a good idea in principle, in practice people felt they wouldn't have time to more than skim that kind of thing. So, the Eclipse option seems like enough.

I'm on the other side of the fence: I know the MDA has a problem in this area, so I have decided to do something about it in detail, and the more detailed abilities are useful.

So, I'm going to close this as WONTFIX for the stack in general. I will continue the MDA-specific work in MDA-65.

Haven't made enough progress to make this a blocker for the IdP V4 release, so deferring it.

I'm a long time user of JaCoCo (with Maven) along with the EclEmma plugin for Eclipse and both work well for Java 8 and Java 11, so I can recommend them.

@Former user mentioned in today's developer call that they are using Cobertura for code coverage, so we should look into that as well.

At first glance, though, it looks like the Cobertura plugin for Maven has been abandoned and doesn't work with Java 11, so it may not be an option after all:

https://github.com/mojohaus/cobertura-maven-plugin/issues/43

This may be an issue with the plugin and not Cobertura itself, so there may be another route to functionality.