[Angular] Replace Observable<undefined> with Observable<{}>

[qmonmert]

No description provided.

[qmonmert]

@mshima WDYT about this update?

[mshima]

Delete api return no content:

generator-jhipster/generators/spring-boot/templates/src/main/java/_package_/_entityPackage_/web/rest/_entityClass_Resource.java.ejs

Line 499 in 36335dd

return ResponseEntity.noContent().headers(HeaderUtil.createEntityDeletionAlert(applicationName, <%= enableTranslation %>, ENTITY_NAME, id<% if (!primaryKey.fields[0].fieldTypeString) { %>.toString()<% } %>)).build();

 {} (Empty Object Type)
{} represents any value except for null and undefined. It is a valid object but has no explicitly defined properties or methods.

So undefined seems for appropriate to the no-content response.

[qmonmert]

ok