code: protected void handleAnnotationGroup(ProtoNetwork protoNetwork,
              Map<String, Annotation> annotationMap, AnnotationGroup ag) {
          if (ag != null) {
              // handle citation
              if (ag.getCitation() != null) {
                  handleCitationAnnotations(protoNetwork, ag.getCitation(),
                          annotationMap);
              }
  
              // handle evidence
              if (ag.getEvidence() != null) {
                  handleEvidenceAnnotations(protoNetwork, ag.getEvidence(),
                          annotationMap);
              }
  
              // handle user annotations (which were already defined)
              if (hasItems(ag.getAnnotations())) {
                  for (Annotation a : ag.getAnnotations()) {
                      annotationMap.put(a.getDefinition().getId(), a);
                  }
              }
          }
      }
docs: Processes an {@link AnnotationGroup} for citations, evidence, and
  user-defined annotations.
  
  @param protoNetwork {@link ProtoNetwork}, the proto network
  @param annotationMap {@link Map}, the annotations map to add to
  @param ag {@link AnnotationGroup}, the annotation group to process