Bug 63840 warning on unused labels
we have warnings for all sorts of unused things. one for unused labels would be good too.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/ProblemSeveritiesConfigurationBlock.java
private static final Key PREF_15_PB_UNCHECKED_TYPE_OPERATION= getJDTCoreKey(JavaCore.COMPILER_PB_UNCHECKED_TYPE_OPERATION);
	private static final Key PREF_15_PB_FINAL_PARAM_BOUND= getJDTCoreKey(JavaCore.COMPILER_PB_FINAL_PARAMETER_BOUND);
	private static final Key PREF_15_PB_VARARGS_ARGUMENT_NEED_CAST= getJDTCoreKey(JavaCore.COMPILER_PB_VARARGS_ARGUMENT_NEED_CAST);
	private static final Key PREF_15_PB_AUTOBOXING_PROBLEM= getJDTCoreKey(JavaCore.COMPILER_PB_AUTOBOXING);
	
	private static final Key PREF_15_PB_MISSING_OVERRIDE_ANNOTATION= getJDTCoreKey(JavaCore.COMPILER_PB_MISSING_OVERRIDE_ANNOTATION);
	private static final Key PREF_15_PB_ANNOTATION_SUPER_INTERFACE= getJDTCoreKey(JavaCore.COMPILER_PB_ANNOTATION_SUPER_INTERFACE);
	private static final Key PREF_15_PB_TYPE_PARAMETER_HIDING= getJDTCoreKey(JavaCore.COMPILER_PB_TYPE_PARAMETER_HIDING);
	private static final Key PREF_15_PB_INCOMPLETE_ENUM_SWITCH= getJDTCoreKey(JavaCore.COMPILER_PB_INCOMPLETE_ENUM_SWITCH);
	private static final Key PREF_15_PB_RAW_TYPE_REFERENCE= getJDTCoreKey(JavaCore.COMPILER_PB_RAW_TYPE_REFERENCE);
	
	private static final Key PREF_PB_SUPPRESS_WARNINGS= getJDTCoreKey(JavaCore.COMPILER_PB_SUPPRESS_WARNINGS);
	private static final Key PREF_PB_UNHANDLED_WARNING_TOKEN= getJDTCoreKey(JavaCore.COMPILER_PB_UNHANDLED_WARNING_TOKEN);
	
	
	private static final String ERROR= JavaCore.ERROR;
	private static final String WARNING= JavaCore.WARNING;
	private static final String IGNORE= JavaCore.IGNORE;
	private static final String ENABLED= JavaCore.ENABLED;
	private static final String DISABLED= JavaCore.DISABLED;
	
	private PixelConverter fPixelConverter;
	
	public ProblemSeveritiesConfigurationBlock(IStatusChangeListener context, IProject project, IWorkbenchPreferenceContainer container) {
		super(context, project, getKeys(), container);
		
		 
		if (ENABLED.equals(getValue(PREF_PB_SIGNAL_PARAMETER_IN_ABSTRACT))) {