public @NotNull CompletableFuture<XDebuggerTreeNode> onReady() {
    CompletableFuture<XDebuggerTreeNode> loaded = myLoaded;  // a copy ref for the lambda in thenCompose()
    return myTreeRestorer != null ? CompletableFuture.allOf(myTreeRestorer.onFinished(), loaded).thenCompose(v -> loaded) : loaded.copy();
  }
public @NotNull CompletableFuture<XDebuggerTreeNode> onReady()