What steps will reproduce the problem?

On Eclipse Luna, try to install jcasgen-m2e-connector from http://cleartk.googlecode.com/git/jcasgen-m2e-connector/org.cleartk.plugin.jcasgen.m2e.repo/target/repository/

What is the expected output?

Installation of the plugin.

What do you see instead?

No update site found at this location.

Is the site just down, or is it at a different location than the one mentioned?

ClearTK no longer provides the jcasgen-m2e-connector. Instead, you should use the jcasgen-maven-plugin from UIMA:

https://uima.apache.org/d/uimaj-2.6.0/tools.html#ugr.tools.jcasgen.maven_plugin

Basically, the UIMA folks took over the jcasgen-maven-plugin that we developed here at ClearTK.