Eclipse Spring Tools missing content assist/ autocomplete

I analyzed the problem of the missing property editor and found the reason (and a solution for it), which is documented here:

Missing Spring Properties Yaml Editor and and Spring Properties Editor with Spring Tools 3.9.2

The answer to the "sub-question" about the application-test.properties file: the content-type that got defined for the Spring Boot property files got defined for specific file names only, since it wasn't possible to put a wildcard-based name like application*.properties in there. But once you opened that file with Open With -> ..., Eclipse will remember your choice for the next double-click.

Future versions of Eclipse (I think it is Photon) will have a more flexible way to define those file name matchings so that we can solve this in future versions.

Follow these steps:

1) Right click on application.properties
2) Open with -> others.. -> search for spring Properties Editor -> tick the use it for all application.properties nd the click om ok.

Select the file you would like to open, i.e. application-xyz.yml

Open with "Generic Editor - Spring YAML Properties"

Check the box: Open *.yaml files. Click OK.

That's it. All *.yml files icons now become Spring-ish look and feel. And from now on, you open any YAML file automatically with "Generic Editor - Spring YAML Properties"