Jersey(2.10.4) Entity provider selection algorithm gives less priority to custom providers(MessageBodyWriter) making it not to be invoked

Question

We have a custom MessageBodyWriter in our application that produces data of Media type application/xml.As we know Jersey 2.x has an algorithm(https://jersey.java.net/documentation/latest/message-body-workers.html#mbw.writer.selection.algorithm) that chooses a suitable MBR from a list of internal and custom MessageBodyWriters to persist entity into output buffer.The algorithm sorts MBR is based upon Object type distance and media type distance.So our Custom MBR is not getting invoked as we saw in the Jersey common code (MessageBodyFactory.getMessageBodyWriter())that our Custom Writer is at the below in the list and some other provider whose isWriteable() method returns true getting invoked.

The question is how can we force Jersey to invoke custom MessageBodyWriters ??Should we try adding a custom media type(like application/vnd.xml) to force it to call Custom types?

Answer 1

I was able to do this by setting jersey.config.workers.legacyOrdering to true in my web.xml file:

<servlet>
    <servlet-name>Jersey</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>

    ...
    
    <init-param>
        <param-name>jersey.config.workers.legacyOrdering</param-name>
        <param-value>true</param-value>
    </init-param>
</servlet>

From the docs:

JAX-RS 2.0 is incompatible with JAX-RS 1.x in one step of the entity provider selection algorithm. JAX-RS 1.x defines sorting keys priorities in the Step 4 in exactly opposite order. So, in JAX-RS 1.x the keys are defined in the order: primary media type, secondary type declaration distance where custom providers have always precedence to internal providers. If you want to force Jersey to use the algorithm compatible with JAX-RS 1.x, setup the property (to ResourceConfig or return from Application from its getProperties method):

jersey.config.workers.legacyOrdering=true