Answer a folder with the matches that are inside it

A project brought into the search by its source folders can link them in from more than one
workspace folder, and accepting every match by the project alone then answers one folder with the
main classes of another. Check where the match itself is as well.

The project checks stay in front of it: a caller can ask with a project's own location rather than
with a workspace folder, and for a project whose description lives outside of the workspace folders
no match is contained in that location.

Author: sorteam

com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/ResolveMainClassHandler.java

@@ -143,7 +143,7 @@ public void acceptSearchMatch(SearchMatch match) {
                                 if (parentPaths.isEmpty()
                                     || ResourceUtils.isContainedIn(project.getLocation(), parentPaths)
                                     || isContainedInInvisibleProject(project, parentPaths)
-                                    || hasSourceFolderContainedIn(project, parentPaths)) {
+                                    || isMatchContainedIn(match, parentPaths)) {
                                     String filePath = null;
 
                                     if (match.getResource() instanceof IFile) {
@@ -259,6 +259,20 @@ private boolean isMainMethod(IMethod method) {
         return false;
     }
 
+    /**
+     * Where the match itself is, for the projects the source folder check brings into the search:
+     * their source folders can be linked in from more than one workspace folder, and a folder is
+     * only asking about the main classes that are in it. The project checks stay in front of this
+     * one - a caller can ask with a project's own location rather than with a workspace folder, and
+     * for a project whose description lives outside of the workspace folders no match would be
+     * contained in that location. A match whose resource has no location falls back to them as well,
+     * since {@link ResourceUtils#isContainedIn} answers false for a null.
+     */
+    private boolean isMatchContainedIn(SearchMatch match, Collection<IPath> rootPaths) {
+        IResource resource = match.getResource();
+        return resource != null && ResourceUtils.isContainedIn(resource.getLocation(), rootPaths);
+    }
+
     /**
      * A project can keep its description outside of the workspace folders and reach the sources
      * through linked folders. The invisible project does it with a single link named after