code: @Reference(name = THREAD_CONTEXT_PROVIDER,
                 service = ThreadContextProvider.class,
                 cardinality = ReferenceCardinality.MULTIPLE,
                 policy = ReferencePolicy.DYNAMIC,
                 policyOption = ReferencePolicyOption.GREEDY)
      protected void setThreadContextProvider(ServiceReference<ThreadContextProvider> ref) {
          String threadContextProviderName = (String) ref.getProperty(COMPONENT_NAME);
          threadContextProviders.putReference(threadContextProviderName, ref);
          if (Boolean.TRUE.equals(ref.getProperty(ThreadContextProvider.ALWAYS_CAPTURE_THREAD_CONTEXT)))
              alwaysEnabled.add(threadContextProviderName);
      }
docs: Declarative Services method for adding a thread context provider.
  
  @param ref reference to the service