guava/src/com/google/common/collect/FluentIterable.java
@Deprecated
  public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
    return checkNotNull(iterable);
  }
@Deprecated
  public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
    return checkNotNull(iterable);
  }
Construct a fluent iterable from another fluent iterable. This is obviously never necessary,
but is intended to help call out cases where one migration from {@code Iterable} to {@code
FluentIterable} has obviated the need to explicitly convert to a {@code FluentIterable}.

@deprecated instances of {@code FluentIterable} don't need to be converted to {@code
FluentIterable}