MissingPluginException(No implementation found for method sendRequest on channel com.example.package_sample/sendAndroid)

Question

I have created a pub package. Inside that package I have used some native libraries and wrote some native code. The package worked perfectly fine before publishing on pub. After publishing package on pub.dev the package throws error where I called the native library. The package I created is here. and I am using the same code as given in example.