It is because you are using explicit SEI and SIB class.
You can put the @SOAPBinding annotation on the SEI and any of the SEI's methods.You can apply this annotation to a type or public methods in a client or server Service Endpoint Interface (SEI), or in a service endpoint implementation class for a
Java beans endpoint.
So if you only specify SIB (do not define explict SEI) then you can use @SOAPBinding on SIB. Here, JSR 181 Processor shall create an implicit SEI from your SIB class and shall apply @SOApBinding on it.
If you remove implements clause from SIB definition, you shall not get this error.
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