RecruitingPhase 2Drug trialOrelabrutinib Plus Rituximab Followed by Maintenance With Orelabrutinib for Relapsed and Refractory Follicular Lymphoma(RR FL)This phase 2 trial studies the efficacy and safety of orelabrutinib plus rituximab followed by maintenance with orelabrutinib for relapsed and refractory follicular lymphoma(RR FL)