Guava, but it's not fully typesafe. Mutable is not part of the Java meta-language used for typing. ImmutableMap implements Map https://guava.dev/releases/23.

Guava, but it's not fully typesafe. Mutable is not part of the Java meta-language used for typing. ImmutableMap implements Map https://guava.dev/releases/23.0/api/docs/com/google/common/collect/ImmutableMap.html https://guava.dev/releases/23.0/api/docs/com/google/common/c... and throws exceptions on mutation. https://guava.dev/releases/23.0/api/docs/src-html/com/google/common/collect/ImmutableMap.html#line.494 https://guava.dev/releases/23.0/api/docs/src-html/com/google...