Even when .NET sdks are used both on the client and on the adapter side, the main Server is based on the java runtime so that it needs a JRE or a JDK to run.

JRE does not provide the “-server” option, that optimizes the HotSpot compiler so that we advice to use a JDK.
For development and non-load-testing scenarios, you could remove the –server option from the startup batch and use the JRE.