allDiagnostics.add(details.source.healthDiagnostics());
            }
            for (WorkSource.Diagnostics diagnostics : allDiagnostics) {
                diagnostics.describeTo(formatter);
            }
        }
    }

    private static class ExecutorWorker implements Runnable {
        private final MergedQueues queue;
        private WorkerLease workerLease;

                    action.accept(failure);
                    return;
                }
            }
            StringDescription description = new StringDescription();
            matcher.describeTo(description);
            throw new AssertionFailedError(String.format("Could not find any failure with description %s, failures:%s\n", description, Joiner.on("\n").join(failures)));
        }

        @Override