How to check out the WTP plugins
It is recommended to check out the plugins via the releng tools using
map files provided by the project.
The main advantage of this approach is to have a reproducable build, and
that way you can easily check out exactly the code that is contained in
builds produced by the web tools project (I-Builds, M-Builds, Releases).
This approach makes general handling easier and is as well more helpful
for the project when submitting bugreports or supplying pachtes.
Checking out HEAD is not recommended as it is not reproducable.
First, download the current releng tools version. The releng tools download is availble at the bottom of the download page for the specific version of Eclipse you have installed.