private void checkContext(boolean canUseClientId) {
    if (urlSigner == null && apiKey == null) {
      throw new IllegalStateException("Must provide either API key or Maps for Work credentials.");
    } else if (!canUseClientId && apiKey == null) {
      throw new IllegalStateException(
          "API does not support client ID & secret - you must provide a key");
    }
    if (urlSigner == null && !apiKey.startsWith("AIza")) {
      throw new IllegalStateException("Invalid API key.");
    }
  }
Shut down this GeoApiContext instance, reclaiming resources. After shutdown() has been called,
no further queries may be done against this instance.
src/main/java/com/google/maps/GeoApiContext.java