| `Hashtable.contains(Object)` and `ConcurrentHashMap.contains(Object)` are legacy | |
| methods for testing if the given object is a value in the hash table. They are | |
| often mistaken for `containsKey`, which checks whether the given object is a | |
| *key* in the hash table. | |
| If you intended to check whether the given object is a key in the hash table, | |
| use `containsKey` instead. If you really intended to check whether the given | |
| object is a value in the hash table, use `containsValue` for clarity. |