void (StackFrameProxyImpl frameProxy) { if (myHistoryKey != null) { myHistories.put(myHistoryKey, getCurrentHistoryTree()); } final String historyKey = getContextKey(frameProxy); final DescriptorTree descriptorTree; if (historyKey != null) { final DescriptorTree historyTree = myHistories.get(historyKey); descriptorTree = (historyTree != null) ? historyTree : new DescriptorTree(true); } else { descriptorTree = new DescriptorTree(true); } deriveHistoryTree(descriptorTree, frameProxy); myHistoryKey = historyKey; }