Mutability (@NotNull Mutability other) { if (this == other) return this; if (this == UNKNOWN || other == UNKNOWN) return UNKNOWN; if (this == MUTABLE || other == MUTABLE) return UNKNOWN; if (this == MUST_NOT_MODIFY || other == MUST_NOT_MODIFY) return MUST_NOT_MODIFY; if (this == UNMODIFIABLE_VIEW || other == UNMODIFIABLE_VIEW) return UNMODIFIABLE_VIEW; return UNMODIFIABLE; }