checkNotNull(entry.getKey());
        checkNotNull(entry.getValue());
      }
      @SuppressWarnings({"unchecked", "rawtypes"})
      // immutable collections are safe for covariant casts
      // and getting the generics right for EnumMap is difficult to impossible
      ImmutableMap<K, V> result = ImmutableEnumMap.asImmutable(new EnumMap(enumMap));
      return result;
    }

    int size = map.size();

    return new IllegalArgumentException(
        "Multiple entries with same " + conflictDescription + ": " + entry1 + " and " + entry2);
  }

  /**
   * A builder for creating immutable map instances, especially {@code public static final} maps
   * ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableMap<String, Integer> WORD_TO_INT =

    return new IllegalArgumentException(
        "Multiple entries with same " + conflictDescription + ": " + entry1 + " and " + entry2);
  }

  /**
   * A builder for creating immutable map instances, especially {@code public static final} maps
   * ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableMap<String, Integer> WORD_TO_INT =