code: public ServiceCall<CredentialsList> listCredentials(ListCredentialsOptions listCredentialsOptions) {
      Validator.notNull(listCredentialsOptions, "listCredentialsOptions cannot be null");
      String[] pathSegments = { "v1/environments", "credentials" };
      String[] pathParameters = { listCredentialsOptions.environmentId() };
      RequestBuilder builder = RequestBuilder.get(RequestBuilder.constructHttpUrl(getEndPoint(), pathSegments,
          pathParameters));
      builder.query("version", versionDate);
      Map<String, String> sdkHeaders = SdkCommon.getSdkHeaders("discovery", "v1", "listCredentials");
      for (Entry<String, String> header : sdkHeaders.entrySet()) {
        builder.header(header.getKey(), header.getValue());
      }
      builder.header("Accept", "application/json");
      return createServiceCall(builder.build(), ResponseConverterUtils.getObject(CredentialsList.class));
    }
docs: List credentials.
  
  List all the source credentials that have been created for this service instance.
  
  **Note:** All credentials are sent over an encrypted connection and encrypted at rest.
  
  @param listCredentialsOptions the {@link ListCredentialsOptions} containing the options for the call
  @return a {@link ServiceCall} with a response type of {@link CredentialsList}