App Add-on - During data input flow .. how to enable user input string to search for an index

[samsign]

As an app add-on creater we don't have control on the Indexes available on the Splunk Cloud on user environment.  In App's Input.config we set the index= default.  

In the add-on flow.. we add a data input  configuration ..with new input stream urls and  the index, it should point to.. shown in the below image 

samsign_1-1693420135881.png

As you see the  index is populated with "default"

How can we enable the

• ability to show up all available indexes in the drop down
• If the desired index is not in the available list .. how can we enable user to  input  a string and trigger a search
• If user don't want to pick a index then.. the default should be selected