When editing an interface, neither "navigate to implementation" (of the interface or one of its methods) works nor any gutter icon is shown. If you remove all module-info files, it works as expected.
Steps to reproduce:
Run the quickstart at https://bitbucket.org/krake-oss/tentackle/src/master/ (section "Project Setup" is sufficient, java 11 or newer, maven 3.6.0 or newer):
mvn archetype:generate -DarchetypeGroupId=org.tentackle -DarchetypeArtifactId=tentackle-project-archetype -DarchetypeVersion=18.104.22.168 -DgroupId=com.example -DartifactId=myapp -Dversion=1.0 -Dpackage=com.example.myapp -Dapplication=MyApp
mvn clean install
Open the class MessageDomainImpl.
Click on the "implements" icon next to "public Message create(...)". The interface MessageDomain will be opened, but there are no gutter icons shown and you cannot navigate back to the implementations.
Remove all module-info.java files and it works as expected.