Configurable code completion list in custom language

In my plugin I have already a completion contributor class which contains some keywords for code completion.

Is there a way to get a customizable code completion list for users of my custom language plugin?

For example: The user of the plugin want to add something to the code completion list like "hello"

So everytime the user hits ctrl + space he will get the a list with all his added strings.



Thanks for your answers.