Enable completion autopopup inside string literal in Go Language Follow

Hi, 
I'm trying to create an auto-complete plugin for Go.
If I type keyword it doesn't automatically show the popup

but it still shows up if I press CTRL+Enter

I've tried to  follow this https://intellij-support.jetbrains.com/hc/en-us/community/posts/206765315-Enable-completion-autopopup-inside-PsiLiteral-for-my-LookupElements?page=1#community_comment_206120595 but still no luck