code: static void printUsage(CliCommand handler, PrintStream out, CmdLineException ex) {
          if (handler == null) {
              printUsage(out);
              return;
          }
          if (getCauseOf(ex, Main.ProcessRuntimeOptionHandler.UnknownRuntimeKind.class) != null) {
              printAvailableRuntimeSources(out);
              return;
          }
  
          // Nested commands can throw errors related to nested handler so report help for the one that failed and the wrapper
          HandlerCmdLineException he = getCauseOf(ex, HandlerCmdLineException.class);
          if (he != null) {
              handler = he.getHandler();
          }
          printUsage(handler, out);
      }
docs: /*package