/guava/android/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
submittingTaskQueue.nextTask = task; checkState( submittingTaskQueue.nextTask == null) ;
checkState ( submittingTaskQueue.nextTask == null ) ; submittingTaskQueue.nextTask = task;
} submitting = Thread.currentThread(); try { ThreadConfinedTaskQueue submittingTaskQueue = requireNonNull(sequencer).latestTaskQueue; if (submittingTaskQueue.thread == submitting) { sequencer = null; <extra_id_0> submittingTaskQueue.nextExecutor = requireNonNull(delegate); delegate = null; } else { Executor localDelegate = requireNonNull(delegate); delegate = null; this.task = task;