Single product bundle option should contain values that point to unique SKU values.
Other sibling options in the bundle may have values that link to SKU linked by other option's value, as long as SKU set scoped to the parent option is unique.
Option A: SKU1, SKU2, SKU3
Option B: SKU4, SKU5, SKU2
Option C: SKU6, SKU7, SKU1
Option A: SKU1, SKU2, SKU2 (invalid because of SKU2)
Option B: SKU1, SKU3, SKU3, SKU4 (invalid because of SKU3)
Option C: SKU5, SKU2, SKU3
Add integration test that fails if NON-UNIQUE SKU is added to cp definition option value
provide private method _validateLinkedCPDefinitionOptionValueRel(CPDefinitionOptionValueRel) that will check current SKU against existing, sibling persisted cp definition option values.