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
inner.setLayout(new GridLayout(nColumns, false));
		excomposite.setClient(inner);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_missing_serial_version_label; 
		addComboBox(inner, label, PREF_PB_MISSING_SERIAL_VERSION, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
				
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_no_effect_assignment_label; 
		addComboBox(inner, label, PREF_PB_NO_EFFECT_ASSIGNMENT, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_accidential_assignement_label; 
		addComboBox(inner, label, PREF_PB_POSSIBLE_ACCIDENTAL_BOOLEAN_ASSIGNMENT, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_finally_block_not_completing_label; 
		addComboBox(inner, label, PREF_PB_FINALLY_BLOCK_NOT_COMPLETING, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_empty_statement_label; 
		addComboBox(inner, label, PREF_PB_EMPTY_STATEMENT, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_char_array_in_concat_label; 
		addComboBox(inner, label, PREF_PB_CHAR_ARRAY_IN_CONCAT, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_hidden_catchblock_label; 
		addComboBox(inner, label, PREF_PB_HIDDEN_CATCH_BLOCK, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		
		
		
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_section_name_shadowing; 
		excomposite= createStyleSection(composite, label, nColumns);
		
		inner= new Composite(excomposite, SWT.NONE);
		inner.setFont(composite.getFont());