android/guava/src/com/google/common/util/concurrent/FluentFuture.java
public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
    return future instanceof FluentFuture
        ? (FluentFuture<V>) future
        : new ForwardingFluentFuture<V>(future);
  }
public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
    return future instanceof FluentFuture
        ? (FluentFuture<V>) future
        : new ForwardingFluentFuture<V>(future);
  }
Converts the given {@code ListenableFuture} to an equivalent {@code FluentFuture}.

<p>If the given {@code ListenableFuture} is already a {@code FluentFuture}, it is returned
directly. If not, it is wrapped in a {@code FluentFuture} that delegates all calls to the
original {@code ListenableFuture}.