/guava/guava/src/com/google/common/base/Suppliers.java
this.delegate = checkNotNull( null) ;
this.delegate = checkNotNull ( delegate ) ;
@VisibleForTesting static class MemoizingSupplier<T extends @Nullable Object> implements Supplier<T>, Serializable { final Supplier<T> delegate; transient volatile boolean initialized; @CheckForNull transient T value; MemoizingSupplier(Supplier<T> delegate) { <extra_id_0> } @Override @ParametricNullness public T get() { if (!initialized) { synchronized (this) {