Adding a dropdown list in a Fiori Element based app is somewhat tricky before. We had a requirement in our project and have checked all these blogs, and one could normally find the solution as redefining the method of class MPC_EXT, as mentioned in the blog
But we can simply achieve this with an annotation.
Most of you might know how to use this, anyways I shall just explain it for a quick understanding for newbies.
Here we are bringing the dropdown list as a filter in a List Report.
Add the mentioned annotation in the CDS which will be consumed as a valueHelp for the respective filter in List Report.
Association is added in the Main CDS where the above CDS is consumed.
Valuehelp is assigned inside select.
Mentioned as selectionField in Metadata Extension. This can be mentioned in CDS also as shown above.
Generate application and Execute. The filter field is displayed as Dropdown List.