Accept types if they are imported when completion

[jdneo]

If types already exist in import declarations, then the completion handler will accept them even if they've been configured in the types filter.

This change should improve the experience for users who develop AWT applications, since the whole AWT package is set in the types filter by default now.

For example, if the compilation unit contains any of the below import declarations, the java.awt.List will appear in the completion list:

• import java.awt.*;
• import java.awt.List;
• import static java.awt.List.*;
• import static java.awt.List.ERROR; (or any other static members from java.awt.List)

fix redhat-developer/vscode-java#1147
fix redhat-developer/vscode-java#1966

Signed-off-by: Sheng Chen sheche@microsoft.com

[rgrunber]

LGTM. Just one small thing that could probably be improved.

[testforstephen]

Current implementation is good for single file. I'm thinking of a different approach to improve it in future. Since the culprit is the typefilter blacklist, we can use existing import declarations of current file to remove the unexpected filter from the blacklist dynamically. This blacklist is a singleton in language server, so it ensures the refreshed blacklist also applies to other files in current project.

I also found unexpected type filters in some other use cases:

• Manually typing import java.awt.|, no result. This is not a good behavior since I'm explicitly asking for a type in package java.awt.
• Hover for quick fix on ActionListener listener;, it suggests to create a class instead of import java.awt.event.ActionListener. Applying typefilter is not a right choice for quickfix.

I'm OK to merge current PR first, and find time to improve other use cases in future PR.

[jdneo]

@testforstephen Thank you for the input. The suggestions make sense to me. I can take some further look in next iteration.