How do you exclude a field from @EqualsAndHashCode?

@EqualsAndHashCode.Exclude on a field removes it from both the equality comparison and the hash code calculation, while every other (non-excluded) field is still used as normal.

@EqualsAndHashCode
public class Session {
    private String userId;

    @EqualsAndHashCode.Exclude
    private long lastAccessedAt;   //  shouldn't affect whether two Session objects are "equal"
}

This matters for fields that are naturally variable or derived rather than part of the object's actual identity — a "last accessed" timestamp, a cached computed value, or a mutable collection whose changing contents shouldn't flip an object's equality (and, more subtly, whose contents changing after being placed in a HashSet could break that set's internal invariants if it were included in the hash code).

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