Issue Description

Currently the generated method all$ for projections does not include fields that start with "on" prefix.

Steps to Reproduce

It is already reproduced by the test here. The same can be reproduced for the union, but there is no such test for the union.

Expected Result

It is expected that onCustomerLocation and onDealerLocation will be included into the all$ method.

Actual Result

Only id, locationType and typename are included.

Your Environment and Setup

• graphql-java-codegen version: 5.8.0
• Build tool: Gradle