code: public static Optional<Map<String, String>> extractOverrideNamespace(Properties properties) {
      if (properties.containsKey(KafkaSchemaRegistryConfigurationKeys.KAFKA_SCHEMA_REGISTRY_OVERRIDE_NAMESPACE)) {
  
        Map<String, String> namespaceOverridesMap = Maps.newHashMap();
        List<String> namespaceOverrides = Lists.newArrayList(SPLIT_BY_COMMA.split(properties
            .getProperty(KafkaSchemaRegistryConfigurationKeys.KAFKA_SCHEMA_REGISTRY_OVERRIDE_NAMESPACE)));
  
        for (String namespaceOverride : namespaceOverrides) {
          List<String> override = Lists.newArrayList(SPLIT_BY_COLON.split(namespaceOverride));
          if (override.size() != 2) {
            throw new RuntimeException("Namespace override should be of the format originalNamespace:replacementNamespace,"
                + " found: " + namespaceOverride);
          }
          namespaceOverridesMap.put(override.get(0), override.get(1));
        }
  
        // If no entry found in the config value, mark it absent
        if (namespaceOverridesMap.size() != 0) {
          return Optional.of(namespaceOverridesMap);
        }
      }
  
      return Optional.<Map<String, String>>absent();
    }
docs: *
  This method extracts Map of namespaces to override in Kafka schema from Config.
  
  Example config:
  kafka.schemaRegistry.overrideNamespace = namespace1:replacement1,namespace2:replacement2
  
  For the above example, this method will create a Map with values:
  {
  "namespace1" : "replacement1",
  "namespace2" : "replacement2"
  }
  
  @param properties Properties properties.
  @return Map of namespace overrides.