Program: 51830
Project: 51830
Buggy source:
/** 
 * Internal method to retrieve linked resource.
 * @param request
 * @param apiCategory
 * @param model
 * @param uuid
 * @param rel
 * @param page
 * @param assembler
 * @param projection
 * @return
 */
private <ID extends Serializable>ResourceSupport findRelInternal(HttpServletRequest request,String apiCategory,String model,ID uuid,String rel,Pageable page,PagedResourcesAssembler assembler,String projection){
  checkModelPluralForm(apiCategory,model);
  DSpaceRestRepository<RestAddressableModel,ID> repository=utils.getResourceRepository(apiCategory,model);
  Class<RestAddressableModel> domainClass=repository.getDomainClass();
  LinkRest linkRest=utils.getLinkRest(rel,domainClass);
  PagedResources<? extends HALResource> result;
  if (linkRest != null) {
    LinkRestRepository linkRepository=utils.getLinkResourceRepository(apiCategory,model,linkRest.name());
    Method linkMethod=repositoryUtils.getLinkMethod(linkRest.method(),linkRepository);
    if (linkMethod == null) {
      throw new RuntimeException("String_Node_Str" + rel + "String_Node_Str"+ linkRest.name()+ "String_Node_Str"+ linkRest.method());
    }
 else {
      try {
        if (Page.class.isAssignableFrom(linkMethod.getReturnType())) {
          Page<? extends RestModel> pageResult=(Page<? extends RestAddressableModel>)linkMethod.invoke(linkRepository,request,uuid,page,projection);
          Link link=linkTo(this.getClass(),apiCategory,model).slash(uuid).slash(rel).withSelfRel();
          Page<HALResource> halResources=pageResult.map(linkRepository::wrapResource);
          halResources.forEach(linkService::addLinks);
          return assembler.toResource(halResources,link);
        }
 else {
          RestModel object=(RestModel)linkMethod.invoke(linkRepository,request,uuid,page,projection);
          Link link=linkTo(this.getClass(),apiCategory,model).slash(uuid).slash(rel).withSelfRel();
          HALResource tmpresult=linkRepository.wrapResource(object);
          tmpresult.add(link);
          return tmpresult;
        }
      }
 catch (      IllegalAccessException|IllegalArgumentException|InvocationTargetException e) {
        throw new RuntimeException(e.getMessage(),e);
      }
    }
  }
  RestAddressableModel modelObject=repository.findOne(uuid);
  DSpaceResource resource=repository.wrapResource(modelObject,rel);
  linkService.addLinks(resource);
  if (resource.getLink(rel) == null) {
    throw new ResourceNotFoundException(rel + "String_Node_Str" + model);
  }
 else   if (resource.getEmbeddedResources().get(rel) instanceof EmbeddedPage) {
    EmbeddedPage ep=(EmbeddedPage)resource.getEmbeddedResources().get(rel);
    List<? extends RestAddressableModel> fullList=ep.getFullList().get(rel);
    if (fullList == null || fullList.size() == 0) {
      return null;
    }
    int start=page.getOffset();
    int end=(start + page.getPageSize()) > fullList.size() ? fullList.size() : (start + page.getPageSize());
    DSpaceRestRepository<RestAddressableModel,?> resourceRepository=utils.getResourceRepository(fullList.get(0).getCategory(),fullList.get(0).getType());
    PageImpl<RestAddressableModel> pageResult=new PageImpl(fullList.subList(start,end),page,fullList.size());
    result=assembler.toResource(pageResult.map(resourceRepository::wrapResource));
    for (    Resource subObj : result) {
      if (subObj.getContent() instanceof HALResource) {
        linkService.addLinks((HALResource)subObj.getContent());
      }
    }
    return result;
  }
 else {
    return (ResourceSupport)resource.getEmbeddedResources().get(rel);
  }
}

Fixed version (ground truth):
/** 
 * Internal method to retrieve linked resource.
 * @param request
 * @param apiCategory
 * @param model
 * @param uuid
 * @param rel
 * @param page
 * @param assembler
 * @param projection
 * @return
 */
private <ID extends Serializable>ResourceSupport findRelInternal(HttpServletRequest request,String apiCategory,String model,ID uuid,String rel,Pageable page,PagedResourcesAssembler assembler,String projection){
  checkModelPluralForm(apiCategory,model);
  DSpaceRestRepository<RestAddressableModel,ID> repository=utils.getResourceRepository(apiCategory,model);
  Class<RestAddressableModel> domainClass=repository.getDomainClass();
  LinkRest linkRest=utils.getLinkRest(rel,domainClass);
  PagedResources<? extends HALResource> result;
  if (linkRest != null) {
    LinkRestRepository linkRepository=utils.getLinkResourceRepository(apiCategory,model,linkRest.name());
    Method linkMethod=repositoryUtils.getLinkMethod(linkRest.method(),linkRepository);
    if (linkMethod == null) {
      throw new RuntimeException("String_Node_Str" + rel + "String_Node_Str"+ linkRest.name()+ "String_Node_Str"+ linkRest.method());
    }
 else {
      try {
        if (Page.class.isAssignableFrom(linkMethod.getReturnType())) {
          Page<? extends RestModel> pageResult=(Page<? extends RestAddressableModel>)linkMethod.invoke(linkRepository,request,uuid,page,projection);
          Link link=linkTo(this.getClass(),apiCategory,model).slash(uuid).slash(rel).withSelfRel();
          Page<HALResource> halResources=pageResult.map(linkRepository::wrapResource);
          halResources.forEach(linkService::addLinks);
          return assembler.toResource(halResources,link);
        }
 else {
          RestModel object=(RestModel)linkMethod.invoke(linkRepository,request,uuid,page,projection);
          Link link=linkTo(this.getClass(),apiCategory,model).slash(uuid).slash(rel).withSelfRel();
          HALResource tmpresult=linkRepository.wrapResource(object);
          tmpresult.add(link);
          return tmpresult;
        }
      }
 catch (      IllegalAccessException|IllegalArgumentException|InvocationTargetException e) {
        throw new RuntimeException(e.getMessage(),e);
      }
    }
  }
  RestAddressableModel modelObject=repository.findOne(uuid);
  DSpaceResource resource=repository.wrapResource(modelObject,rel);
  linkService.addLinks(resource);
  if (resource.getLink(rel) == null) {
    throw new ResourceNotFoundException(rel + "String_Node_Str" + model);
  }
 else   if (resource.getEmbeddedResources().get(rel) instanceof EmbeddedPage) {
    EmbeddedPage ep=(EmbeddedPage)resource.getEmbeddedResources().get(rel);
    List<? extends RestAddressableModel> fullList=ep.getFullList();
    if (fullList == null || fullList.size() == 0) {
      return null;
    }
    int start=page.getOffset();
    int end=(start + page.getPageSize()) > fullList.size() ? fullList.size() : (start + page.getPageSize());
    DSpaceRestRepository<RestAddressableModel,?> resourceRepository=utils.getResourceRepository(fullList.get(0).getCategory(),fullList.get(0).getType());
    PageImpl<RestAddressableModel> pageResult=new PageImpl(fullList.subList(start,end),page,fullList.size());
    result=assembler.toResource(pageResult.map(resourceRepository::wrapResource));
    for (    Resource subObj : result) {
      if (subObj.getContent() instanceof HALResource) {
        linkService.addLinks((HALResource)subObj.getContent());
      }
    }
    return result;
  }
 else {
    return (ResourceSupport)resource.getEmbeddedResources().get(rel);
  }
}