code: public Response<ConfigurationSetting> updateSetting(String key, String value) {
          return updateSetting(new ConfigurationSetting().key(key).value(value));
      }
docs: Updates an existing configuration value in the service with the given key. The setting must already exist.
  
  <p><strong>Code Samples</strong></p>
  
  <pre>
  ConfigurationSetting result = client.updateSetting("prodDCConnection", "db_connection");
  System.out.printf("Key: %s, Value: %s", result.key(), result.value());</pre>
  
  @param key The key of the configuration setting to update.
  @param value The updated value of this configuration setting.
  @return The {@link ConfigurationSetting} that was updated, or {@code null}, if the configuration value does not
  exist, is locked, or the key is an invalid value (which will also throw ServiceRequestException described below).
  @throws IllegalArgumentException If {@code key} is {@code null}.
  @throws ServiceRequestException If a ConfigurationSetting with the key does not exist or the configuration value
  is locked. Or, if {@code key} is an empty string.