What comes next?

Number Theory Level pending

Suppose there is an operation $$\oplus$$ such that

$1 \oplus 2 \oplus 3 = 9$ $2 \oplus 3 \oplus 4 = 2$ $3 \oplus 4 \oplus 5 = 8$ $4 \oplus 5 \oplus 6 = 9.$

What is the value of $5 \oplus 6 \oplus 7 = ?$

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