JcrHippoRepository can invoke HippoRepositoryFactory.getHippoRepository() concurrently which makes unit tests fail

In org.hippoecm.hst.core.jcr.pool.JcrHippoRepository#initHippoRepository, when the repositoryURI is empty (in unit tests the case), the code

if (StringUtils.isEmpty(repositoryURI)) {
                    hippoRepository = HippoRepositoryFactory.getHippoRepository();
                }

throws an exception when another thread already invoked

HippoRepositoryFactory.getHippoRepository()

before. This can happen because there is the pooling repositories that trigger org.hippoecm.hst.core.jcr.pool.JcrHippoRepository#initHippoRepository (for example from hst event listeners) but also the 'delegating' repository triggers org.hippoecm.hst.core.jcr.pool.JcrHippoRepository#initHippoRepository : However, the delegating repositories (id="javax.jcr.Repository.delegating") use a different backing JcrHippoRepository instance than the pooling repositories.