How to see m2e connectors installed?
I have installed Tycho m2e connector as described here: http://codeandme.blogspot.ru/2012/12/tycho-build-1-building-plug-ins.html
It was said to "Go to Preferences/Maven/Discovery and click on Open Catalog. Find and select the Tycho Configurator".
When I was doing this first time, Tycho appearead in the list and I installed it. Later, when I repeated the same thing second time, Tycho didn't appear in search result.
This probably because it was already installed.
So, how to be sure? How to check the list of things, installed for m2e and see tycho there?
Answer
m2e connectors are discovered via a special catalog, but in the end they are installed just like any normal feature. So once they are installed, you'll find them listed with the other features under Help > About > Installation Details.
Knowing that the Tycho connector is called "Tycho Project Configurators", you can find out if you have that connector installed.
But what if you don't know the name of the connector you are looking for? Or you don't know if some installed feature is an m2e connector? In this case, the only solution I could find was to look into the data behind the catalog. The catalog URL is shown in the configuration under Maven > Discovery. The XML file at that URL points to another location with a JAR file (in my m2e 1.4 installation, this pointed here), and in the JAR file there is a plugin.xml with the raw catalog data.
There, you can for example find the feature ID of the Tycho connector, which is the same ID as shown in the Installation Details dialog:
<iu id="org.sonatype.tycho.m2e.feature.feature.group" />
This is all not very convenient, but if you need the definite answer, you can find it there. E.g. I found out that I have an old version of the Tycho connector installed. If this is also the case for you, just uninstall the connector and have m2e automatically discover the connectors you need. This installed the right connector version for my m2e version.