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Arrays of primitive types are not exempt from this guideline. As arrays are objects in Java, if a reference to an array is returned, the caller may freely modify the contents of the original array. Shallow copies of arrays of primitive types can be safely returnedare safe to return.
If the class has a public setter method, this guideline still applies. Note that a setter method may perform input validation and sanitization before setting the internal fields. On the other hand, returning references to internal objects may allow the caller to incorporate none of these measures.
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