Bug 582305 Improve Leak Suspects report for references in paths

Fix command printing for commands such as:
path2gc 0x0 -exclude;
where the -exclude was omitted leading to default values being used
next time.
Use excludes on path2gc root for single object leak to find involved
thread.

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=582305
Change-Id: I6f56548a6be6e0dc34e4536b6a563c729bf9b9f6

plugins/org.eclipse.mat.api/src/org/eclipse/mat/inspections/LeakHunterQuery.java

@@ -461,11 +461,12 @@ else if (snapshot.isClass(accumulationPointId))
         {
             IResult result = SnapshotQuery.lookup("path2gc", snapshot) //$NON-NLS-1$
                             .setArgument("object", describedObject) //$NON-NLS-1$
+                            .setArgument("excludes", excludes) //$NON-NLS-1$
                             .execute(listener);
             qspath = new QuerySpec(Messages.LeakHunterQuery_ShortestPaths, result);
             StringBuilder sb = new StringBuilder("path2gc"); //$NON-NLS-1$
             sb.append(" 0x").append(Long.toHexString(describedObject.getObjectAddress())); //$NON-NLS-1$
-            //addExcludes(sb);
+            addExcludes(sb);
             qspath.setCommand(sb.toString());
             // See if the end of the path is a thread
             if (!isThreadRelated && result instanceof IResultTree && result instanceof ISelectionProvider)
@@ -1022,13 +1023,17 @@ void addExcludes(StringBuilder sb)
         if (excludes != null && !excludes.isEmpty() || hasDefault)
         {
             sb.append(" -excludes"); //$NON-NLS-1$
-            if (excludes != null)
+            if (excludes != null && !excludes.isEmpty())
             {
                 for (String ex : excludes)
                 {
                     sb.append(' ').append(Converters.convertAndEscape(String.class, ex));
                 }
             }
+            else
+            {
+                sb.append(' ');
+            }
             sb.append(';');
         }
     }
@@ -1345,6 +1350,7 @@ private ThreadInfoQuery.Result extractThreadData(SuspectRecord suspect, Set<Stri
                 {
                     IResultTree tree = (IResultTree) SnapshotQuery.lookup("merge_shortest_paths", snapshot) //$NON-NLS-1$
                                     .setArgument("objects", acc) //$NON-NLS-1$
+                                    .setArgument("excludes", excludes) //$NON-NLS-1$
                                     .execute(listener);
                     for (Object row : tree.getElements())
                     {