[Java] support for bearer authentication

Created by: lorenzleutgeb

Please see swagger-api/swagger-codegen-generators#113

The output that OpenAPI generator 020883fd produces suffers from the same defect. However I did not look into your codebase. I understand that referring to the Swagger Codegen project might not be the most sensible thing to do, and if you rather do not want to look at it, I could look for the cause in this codebase.