// Duplicate entries cause errors, so prep them with a set
HashSet<IClasspathEntry> entries = new HashSet<IClasspathEntry>();
// VM
entries.add(JavaCore.newContainerEntry(vmPath.makeAbsolute())); // JVM
// Processing Libraries
IPath plibs = new Path(ProcessingCore.getCore().getCoreJarFile().getAbsolutePath());
entries.add(JavaCore.newLibraryEntry( plibs, null, null, false ));