Bug 52064 Content assist in "New Class" Dialog shows interfaces
Content Assist is available for the superclass in M7. However it also lists interfaces. If an interface is selected, the generated class "extends" it instead of "implementing" it.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/wizards/NewTypeWizardPage.java
CompilationUnit root= (CompilationUnit) parser.createAST(null);
		IProblem[] problems= root.getProblems();
		ArrayList res= new ArrayList();
		for (int i= 0; i < problems.length; i++) {
			if (problems[i].getID() == IProblem.UnusedImport) {
				String imp= problems[i].getArguments()[0];
				res.add(imp);
			}
		}
		if (!res.isEmpty()) {
			ImportsManager imports= new ImportsManager(cu);
			for (int i= 0; i < res.size(); i++) {
				String curr= (String) res.get(i);
				imports.removeImport(curr);
			}
			imports.create(needsSave, null);
		}
	}
	/**
	 * Uses the New Java file template from the code template page to generate a
	 * compilation unit with the given type content.
	 * @param cu The new created compilation unit
	 * @param typeContent The content of the type, including signature and type
	 * body.
	 * @param lineDelimiter The line delimiter to be used.
	 * @return String Returns the result of evaluating the new file template
	 * with the given type content.
	 * @throws CoreException
	 * @since 2.1
	 */