Bug 45062 Don't filter output folder and class files
Create a Java project with source folder src and output folder bin. The bin folder will not be shown in the Packages Explorer. Create a Java project with source folder src and output folder output/bin. The output and bin folders are shown in the Packages Explorer. Implictly filtering out bin is confusing and inconsistent. A better way to do this would be to use a name filter for bin or add "Output folder" to the list of available filters.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
}
				boolean changed= false;
				for (Iterator iter= is.iterator(); iter.hasNext();) {
					Object element= iter.next();
					if (element instanceof IJavaProject) {
						IProject project= ((IJavaProject)element).getProject();
						if (!project.isOpen()) {
							ns.add(project);
							changed= true;
						}
					} else if (element instanceof IProject) {
						IProject project= (IProject)element;
						if (project.isOpen()) {
							IJavaProject jProject= JavaCore.create(project);
							if (jProject != null && jProject.exists())
								ns.add(jProject);
								changed= true;
						}
					}
				}
				if (changed) {
					newSelection= new StructuredSelection(ns);
					setSelection(newSelection);
				}
				super.handleInvalidSelection(invalidSelection, newSelection);
			}
		};
	}
	/**
	 * Answers whether this part shows the packages flat or hierarchical.