code: <T> T getDefault(String mpConfigPropName, T defaultValue) {
          MPConfigAccessor accessor = cmProvider.mpConfigAccessor;
          if (accessor != null) {
              Object mpConfig = mpConfigRef.get();
              if (mpConfig == Boolean.FALSE) // not initialized yet
                  if (!mpConfigRef.compareAndSet(Boolean.FALSE, mpConfig = accessor.getConfig()))
                      mpConfig = mpConfigRef.get();
  
              if (mpConfig != null)
                  defaultValue = accessor.get(mpConfig, mpConfigPropName, defaultValue);
          }
          return defaultValue;
      }
docs: Obtain a default value from MicroProfile Config if available.
  
  @param mpConfigPropName name of the MicroProfile Config property.
  @param defaultValue value to use if not found in MicroProfile Config.
  @return default value.