hei Leif, nice picture. Are you sure this bird an immature ? the yellow eye, the glossy black parts and the beak are for me an adult. Am I wrong ?

Not entirely an adult. The eye is not as pale as the typical adult (almost white eyes) and the bird still has a few juvenile/immature brown feathers on breast. It also seems to me that the white breast band is not yet complete, not as clear as in adults.
The bird could be called a sub-adult.
Immature / juvenile Superb Starling has brownish head and breast without white breast band, and brown eyes which soon gets paler with age.

Thanks Thomas, I agree with your argumentation.

Best regards Leif