@Override
    public boolean canFindUsages(PsiElement element) {
        if (element == null) return false;
        if (element.getContainingFile() == null) return false;
        if (element.getContainingFile().getVirtualFile() == null) return false;
        String extension = element.getContainingFile().getVirtualFile().getExtension();
        return ("sd".equals(extension) || "profile".equals(extension));
    }
This class is used for the extension (in plugin.xml) to the class SdFindUsagesHandler.

@author Shahar Ariel
integration/intellij/src/main/java/ai/vespa/intellij/schema/findUsages/SdFindUsagesHandlerFactory.java