sometimes the following exception occurs in JdtsTestFinder(see below.)
This happens when rrp.length() == thisFilePath.length(),
and
thisFilePath.substring(thisFilePath.length() + 1) is actually called, what
leads to SIOOBE.
Exact conditions (exact node names) are not known, but
the request is to make the code more safe to bypass such situation.

//Exception in thread "Test Tree Cache Worker" java.slang.StringIndexOutOfBoundsException: String index out of range: -1
//at java.lang.String.substring(String.java:1768)
//at java.lang.String.substring(String.java:1735)
//at com.sun.javatest.TRT_TreeNode.makeNodeRelative(TRT_TreeNode.java:1285)
//at com.sun.javatest.TRT_TreeNode.insertFinderFiles(TRT_TreeNode.java:1046)
//at com.sun.javatest.TRT_TreeNode.processFile(TRT_TreeNode.java:1030)
//at com.sun.javatest.TRT_TreeNode.scanIfNeeded(TRT_TreeNode.java:613)
//at com.sun.javatest.TRT_TreeNode.getChildCount(TRT_TreeNode.java:94)
//at com.sun.javatest.TRT_Iterator$PseudoFrame.nextIndex(TRT_Iterator.java:885)
//at com.sun.javatest.TRT_Iterator.findNext(TRT_Iterator.java:580)
//at com.sun.javatest.TRT_Iterator.nextElement(TRT_Iterator.java:160)
//at com.sun.javatest.TRT_Iterator.next(TRT_Iterator.java:181)
//at com.sun.javatest.exec.TT_NodeCache.process(TT_NodeCache.java:539)
//at com.sun.javatest.exec.TT_NodeCache.run(TT_NodeCache.java:69)
//at com.sun.javatest.exec.TestTreeModel$CacheWorker.run(TestTreeModel.java:851)

-----------------------------
}
else {
// path seems to be relative to the root of the testsuite
String rrp = TestResultTable.getRootRelativePath(this);
String thisFilePath = file.getPath().replace(File.separatorChar, '/');

if (debug > 1)
Debug.println(" -> check for RRP against: " + rrp);

if (rrp != null && rrp.length() != 0 && thisFilePath.startsWith(rrp)) {
// strip length of fullPath
if (debug > 1)
Debug.println(" -> URL is root relative, stripping");

int distToDel = (rrp == null ? 0 : rrp.length());

// zap leading path plus the last path sep.
String platformPath = thisFilePath.substring(distToDel + 1); // *** line 1285

return platformPath;
}