public static synchronized DiagnosticGroup forType(DiagnosticType type) {
    singletons.computeIfAbsent(type, DiagnosticGroup::new);
    return singletons.get(type);
  }
public static synchronized DiagnosticGroup forType ( DiagnosticType type ) { singletons . computeIfAbsent ( type , DiagnosticGroup :: new ) ; return singletons . get ( type ) ; }
Create a diagnostic group that matches only the given type.