Bug 23968 Abusive check on task tags
2.1M1 Java UI ensures that task tags are valid Java identifiers. Why is it so ? JDT/Core supports any type of tags. In particular, "TODO:" should work fine, and was one of the mentionned tags on the original feature request.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/CompilerPreferencePage.java
String[] errorWarningIgnoreLabels= new String[] {
			JavaUIMessages.getString("CompilerPreferencePage.error"),  
			JavaUIMessages.getString("CompilerPreferencePage.warning"), 
			JavaUIMessages.getString("CompilerPreferencePage.ignore") 
		};
			
		GridLayout layout= new GridLayout();
		layout.numColumns= 2;
		layout.verticalSpacing= 2;
		Composite warningsComposite= new Composite(folder, SWT.NULL);
		warningsComposite.setLayout(layout);
		Label description= new Label(warningsComposite, SWT.WRAP);
		description.setText(JavaUIMessages.getString("CompilerPreferencePage.warnings.description")); 
		GridData gd= new GridData();
		gd.horizontalSpan= 2;
		gd.widthHint= convertWidthInCharsToPixels(50);
		description.setLayoutData(gd);
		String label= JavaUIMessages.getString("CompilerPreferencePage.pb_unreachable_code.label"); 
		addComboBox(warningsComposite, label, PREF_PB_UNREACHABLE_CODE, errorWarningIgnore, errorWarningIgnoreLabels, 0);	
		
		label= JavaUIMessages.getString("CompilerPreferencePage.pb_invalid_import.label"); 
		addComboBox(warningsComposite, label, PREF_PB_INVALID_IMPORT, errorWarningIgnore, errorWarningIgnoreLabels, 0);
		label= JavaUIMessages.getString("CompilerPreferencePage.pb_unused_local.label"); 
		addComboBox(warningsComposite, label, PREF_PB_UNUSED_LOCAL, errorWarningIgnore, errorWarningIgnoreLabels, 0);
		label= JavaUIMessages.getString("CompilerPreferencePage.pb_overriding_pkg_dflt.label"); 
		addComboBox(warningsComposite, label, PREF_PB_OVERRIDING_PACKAGE_DEFAULT_METHOD, errorWarningIgnore, errorWarningIgnoreLabels, 0);			
		label= JavaUIMessages.getString("CompilerPreferencePage.pb_method_naming.label"); 
		addComboBox(warningsComposite, label, PREF_PB_METHOD_WITH_CONSTRUCTOR_NAME, errorWarningIgnore, errorWarningIgnoreLabels, 0);			
		label= JavaUIMessages.getString("CompilerPreferencePage.pb_hidden_catchblock.label");