code: private void deregisterRemovableTargets(TrafficSource trafficSource,
                                            BaragonGroup baragonGroup,
                                            TargetGroup targetGroup,
                                            Collection<BaragonAgentMetadata> agents,
                                            Collection<TargetDescription> targets) {
      Collection<TargetDescription> removableTargets = listRemovableTargets(trafficSource, baragonGroup, targets, agents);
  
      for (TargetDescription removableTarget : removableTargets) {
        try {
          if (configuration.isPresent()
              && !configuration.get().isRemoveLastHealthyEnabled()
              && isLastHealthyInstance(removableTarget, targetGroup)) {
            LOG.info("Will not de-register target {} because it is last healthy instance in {}", removableTarget, targetGroup);
          } else {
            elbClient.deregisterTargets(new DeregisterTargetsRequest()
                .withTargetGroupArn(targetGroup.getTargetGroupArn())
                .withTargets(removableTarget));
            LOG.info("De-registered target {} from target group {}", removableTarget, targetGroup);
          }
        } catch (AmazonClientException acexn) {
          LOG.error("Could not de-register target {} from target group {} due to error",
              removableTarget, targetGroup, acexn);
          exceptionNotifier.notify(acexn, ImmutableMap
              .of("targetGroup", targetGroup.getTargetGroupName()));
        }
      }
    }
docs: De-register any targets representing agents that are not known to the BaragonService,
  or which otherwise need to be removed.
  
  @param targetGroup TargetGroup to check for old agents
  @param agents Known agents, to be used as a reference sheet