@Override
  public <T> T invoke(
      String methodName, Object argument, Class<T> returnType, Map<String, String> extraHeaders)
      throws Throwable {
    return innerClient.invoke(methodName, argument, returnType);
  }
Adapter that allows using a {@link JsonRpcLambdaClient} as the transport for jsonrpc4j's dynamic
client proxy by implementing the {@link IJsonRpcClient} interface.

<p>This class is package-local, because it should only be used through the {@link
JsonRpcLambdaClient#newProxy(Class)} method.
json-rpc-lambda-client/src/main/java/com/amazonaws/blox/jsonrpc/JsonRpcLambdaProxyAdapter.java