Fix: Server sent event on registration for application is not emmitted

Author: joshiste

spring-boot-admin-server/src/main/java/de/codecentric/boot/admin/server/web/ApplicationsController.java

@@ -75,6 +75,7 @@ public Flux<Application> applications() {
  @GetMapping(path = "/applications/{name}", produces = MediaType.APPLICATION_JSON_VALUE)
  public Mono<ResponseEntity<Application>> application(@PathVariable("name") String name) {
  return this.toApplication(name, registry.getInstances(name).filter(Instance::isRegistered))
+ .filter(a -> !a.getInstances().isEmpty())
  .map(ResponseEntity::ok)
  .defaultIfEmpty(ResponseEntity.notFound().build());
  }
@@ -106,7 +107,7 @@ protected Tuple2<String, Flux<Instance>> getApplicationForInstance(Instance inst
  }
 
  protected Mono<Application> toApplication(String name, Flux<Instance> instances) {
- return instances.collectList().filter(instanceList -> !instanceList.isEmpty()).map(instanceList -> {
+ return instances.collectList().map(instanceList -> {
  Application group = new Application(name);
  group.setInstances(instanceList);
  group.setBuildVersion(getBuildVersion(instanceList));