code: @Nonnull
      public static <K, V> Map<K, V> asImmutableMap(@Nullable Object... a) {
          return putAllAndMakeImmutable(new LinkedHashMap<K, V>(), a);
      }
docs: Returns a {@link LinkedHashMap}
  with the mappings <code>a[0] => a[1], a[2] => a[3], ...</code>.
  @param a the elements to construct a {@link Map} from.
  @return a immutable {@link Map} constructed of the specified elements.