How can a type have multiple supertypes which are array types, and not itself be an array type?

Question

I'm trying to code an implementation of type inference, using the algorithm outlined in the Java spec, at https://docs.oracle.com/javase/specs/jls/se8/html/jls-18.html#jls-18.2.3

There is a line here with some implications I'm struggling to understand:

"...among the supertypes of S that are array types, a most specific type is identified, S'[] (this may be S itself)."

How can S itself not be the most specific array type? In other words, how can a type have supertypes which are array types, and not itself be an array type (and therefore of the most specific kind)?

Am I missing something obvious here?

Thanks for any insight anyone can offer...

Answer 1

Say you have a Double[] and the options are Number[] or Object[] then Number[] is the most specific match. When performing type inference, there might be multiple constraints. It might even infer the type (Serializable[] & Comparable[])