code: private boolean shouldAddWeakRelationTarget(CmsResource weakRelationTarget) {
  
          for (String typeName : VALID_WEAK_RELATION_TARGET_TYPES) {
              if (OpenCms.getResourceManager().matchResourceType(typeName, weakRelationTarget.getTypeId())) {
                  return true;
              }
          }
          return false;
      }
docs: Checks if the resource should be added to the related resources even if the relation pointing to it is a weak relation.<p>
  
  @param weakRelationTarget the relation target resource
  @return true if the resource should be added as a related resource