Recall that immutability offers several benefits such as thread-safety, prevention against inadvertent modification of fields, and malicious tampering. Class invariants and state of immutable objects are always consistent with their requirements, so no defensive copying is necessary. However, sometimes it is not possible to make sensitive classes immutable. Fortunately, there is a mechanism that allows code to expose mutable classes to untrusted code by granting read-only access. This is largely achieved through unmodifiable wrappers. For example, the Collection classes include a set of wrappers that allow clients to observe an unmodifiable view of the particular a Collection object.
Noncompliant Code Example
...