private static void loadPropertiesFromURL(Properties properties, URL url) {
    if (url != null) {
      try {
        properties.load(url.openStream());
      } catch (IOException io) {
        throw new GemFireIOException(
            String.format("Failed reading %s", url), io);
      }
    }
  }
For every key in p mark it as being from the given source.
geode-core/src/main/java/org/apache/geode/distributed/internal/DistributionConfigImpl.java