docs: @SuppressWarnings("unchecked")
      public Map<String, String> getSystemJavaxPersistenceOverrides() {
          if(propertyOverridesExist()) {
              // we make use of a type cast hack to convert Properties to a Map
              return mergeFilteredMaps(System.getenv(), (Map) System.getProperties());
          }
          return null;
      }