ExecutorService's type parameters changed between JDK5 and JDK6 in a way that makes it impossible for our invokeAll/invokeAny methods to match both at compile time. This project builds a JDK6-like copy of ExecutorService (but with JDK5 compiler settings to ensure that it will work with JRE5 at runtime). This project's is then used in the bootstrap class path of Guava proper.