code: @FFDCIgnore(value = { InterruptedException.class })
      public void checkinClient(Client client) {
          boolean done = false;
  
          //If no more space. Return. Shouldn't be checking more than we have. Shouldn't happen besides unit test anyways.
          if (clients.remainingCapacity() == 0) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isEventEnabled()) {
                  Tr.event(tc, "Checking in more clients than there should be.");
              }
              return;
          }
  
          while (!done) {
              try {
                  //check if this client was already checked-in.
                  if (!clients.contains(client)) {
                      clients.putFirst(client);
                      if (TraceComponent.isAnyTracingEnabled() && tc.isEventEnabled()) {
                          int clientHash = (client != null) ? client.hashCode() : 0;
                          Tr.event(tc, "post-checkin  - (" + clientHash + ") " + (numClients - clients.remainingCapacity()) + " of " + numClients + " clients available.");
                      }
                  }
                  done = true;
              } catch (InterruptedException e) {
                  if (TraceComponent.isAnyTracingEnabled() && tc.isEventEnabled())
                      Tr.event(tc, "InterruptedException during checkin - will retry");
              }
          }
  
      }
docs: /*
  Checks in a client.