An example of a custom request converter for Retrofit

NewPasteParametersConverter.java

class NewPasteParametersConverter implements Converter<NewPasteParameters, RequestBody> {

    @Override
    public RequestBody convert(NewPasteParameters value) throws IOException {
        FormBody.Builder requestBodyBuilder = new FormBody.Builder()
                .add("api_paste_code", value.getText());
                
        if (value.getTitle() != null) {
            requestBodyBuilder.add("api_paste_name", value.getTitle());
        }
        if (value.getFormat() != null) {
            requestBodyBuilder.add("api_paste_format", value.getFormat().toString());
        }
        if (value.getVisibility() != null) {
            requestBodyBuilder.add("api_paste_private", value.getVisibility().toString());
        }
        if (value.getExpiryDate() != null) {
            requestBodyBuilder.add("api_paste_expire_date", value.getExpiryDate().toString());
        }
        
        return requestBodyBuilder.build();
    }
}