The java files were automatically generated from toolchain.xsd with the following command:
xjc -d ../../../../../../.. -p de.uni_freiburg.informatik.ultimate.core.lib.toolchain toolchain.xsd

xjc should be distributed with any variety of Java JDK 6.0. 
Mac users might have to look for it under /System/Library/Frameworks/JavaVM.framework/Commands.
Windows users may have to set their PATH environemnt variable to JDK-Folder/bin.
