Sonar Java Web Client: Authors by line null

When running the following code on my Sonar, measure returns null. (Should return something on the lines of "1=author;2=author..."). However it works on nemo.sonarsource.org.

Other measures eg: violation work correctly on mine so this is probably not a question of faulty code. I suspect I need to configure Sonar somehow?

    private final Sonar sonar;
 
     public String getAuthors(String resourceKey){
          return getMeasure(resourceKey, "authors_by_line").getData();
     }
 
     private Measure getMeasure(String resourceKey, String measureName){
         Resource resource = sonar.find(ResourceQuery.createForMetrics(
             resourceKey, measureName));
 
         Measure measure = resource.getMeasure(measureName);
 
         return measure;
    }
 

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