The document says:
Returns
The found web elements or
nullif cannot find any.
I think this sentence is ambiguous. The word “web element” is not defined here.
Why not the document explicitly says that the keyword returns a List of org.openqa.selenum.WebElement object?
Many of the Katalon Studio users aren’t skilled enough for Java programming, and they are not aware that that they are supposed to write the required import statements for themselves.
The document should explicitly explain that users have to write the required import statement. Otherwise they would keep on posting in this User Forum asking how to fix the errors like this.