android/guava/src/com/google/common/collect/ImmutableSortedMap.java
@Override
  public ImmutableSortedMap<K, V> tailMap(K fromKey, boolean inclusive) {
    return getSubMap(keySet.tailIndex(checkNotNull(fromKey), inclusive), size());
  }
@Override
  public ImmutableSortedMap<K, V> tailMap(K fromKey, boolean inclusive) {
    return getSubMap(keySet.tailIndex(checkNotNull(fromKey), inclusive), size());
  }
This method returns a {@code ImmutableSortedMap}, consisting of the entries whose keys are
greater than (or equal to, if {@code inclusive}) {@code fromKey}.

<p>The {@link SortedMap#tailMap} documentation states that a submap of a submap throws an
{@link IllegalArgumentException} if passed a {@code fromKey} less than an earlier {@code
fromKey}. However, this method doesn't throw an exception in that situation, but instead keeps
the original {@code fromKey}.

@since 12.0