android/guava/src/com/google/common/collect/ImmutableMap.java
public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
    checkEntryNotNull(k1, v1);
    checkEntryNotNull(k2, v2);
    checkEntryNotNull(k3, v3);
    return RegularImmutableMap.create(3, new Object[] {k1, v1, k2, v2, k3, v3});
  }
public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
    checkEntryNotNull(k1, v1);
    checkEntryNotNull(k2, v2);
    checkEntryNotNull(k3, v3);
    return RegularImmutableMap.create(3, new Object[] {k1, v1, k2, v2, k3, v3});
  }
Returns an immutable map containing the given entries, in order.

@throws IllegalArgumentException if duplicate keys are provided