the [Guava Beta Checker] to ensure that you do not use any `@Beta` APIs!**

2.  APIs without `@Beta` will remain binary-compatible for the indefinite
    future. (Previously, we sometimes removed such APIs after a deprecation
    period. The last release to remove non-`@Beta` APIs was Guava 21.0.) Even
    `@Deprecated` APIs will remain (again, unless they are `@Beta`). We have no
    plans to start removing things again, but officially, we're leaving our

@GwtCompatible
@ElementTypesAreNonnullByDefault
@SuppressWarnings({"AndroidJdkLibsChecker", "Java7ApiChecker"})
@IgnoreJRERequirement // Users will use this only if they're already using streams.
@Beta // TODO: b/288085449 - Remove.
public final class MoreCollectors {

  /*
   * TODO(lowasser): figure out if we can convert this to a concurrent AtomicReference-based
   * collector without breaking j2cl?
   */