apollo-mockserver/src/main/java/com/ctrip/framework/apollo/mockserver/EmbeddedApollo.java/EmbeddedApollo/mergeOverriddenProperties
class EmbeddedApollo:  private Map<String, String> mergeOverriddenProperties(String namespace, Map<String, String> configurations) {
    if (addedOrModifiedPropertiesOfNamespace.containsKey(namespace)) {
      configurations.putAll(addedOrModifiedPropertiesOfNamespace.get(namespace));
    }
    if (deletedKeysOfNamespace.containsKey(namespace)) {
      for (String k : deletedKeysOfNamespace.get(namespace)) {
        configurations.remove(k);
      }
    }
    return configurations;
  }