code: public @Nullable <Z> Z mapWithCopyQuietly(Function<T, Z> function) {
          final @Nullable SharedReference<T> localRef = getCopy();
          try {
              if (localRef == null) {
                  return function.apply(null);
              } else {
                  return function.apply(localRef.get());
              }
          } finally {
              if (localRef != null) Closeables2.closeQuietly(localRef, log);
          }
      }
docs: Just like mapWithCopy() except that this silently swallows any exception
  that calling close() on the copy might throw.
  
  @param function The function to apply to the value of the local reference.
  @param <Z> The type of object produced by the function.
  @return The value that was produced by the supplied {@code function}.