private InputStream getSimpleInputStream() {
    ImmutableList<String> settingsFiles = ImmutableList.<String>builder()
        .add(COMMON_SETTINGS_PATH)
        .add(ENV_COMMON_SETTINGS_PATH)
        .add(API_SETTINGS_PATH)
        .add(ENV_API_SETTINGS_PATH)
        .add(EXTENSION_SETTINGS_PATH)
        .add(TRANSFER_SETTINGS_PATH)
        .add(ENV_TRANSFER_SETTINGS_PATH)
        .build();
    return ConfigUtils.getCombinedInputStream(settingsFiles);
  }
{@link SettingsExtension} that reads configuration from YAML files on the classpath.
extensions/config/portability-config-yaml/src/main/java/org/datatransferproject/config/yaml/YamlSettingsExtension.java