diff --git a/geoportal-service/src/main/java/org/gcube/application/geoportal/service/engine/providers/ucd/UCDManager.java b/geoportal-service/src/main/java/org/gcube/application/geoportal/service/engine/providers/ucd/UCDManager.java
index 6b84dd9..3b131be 100644
--- a/geoportal-service/src/main/java/org/gcube/application/geoportal/service/engine/providers/ucd/UCDManager.java
+++ b/geoportal-service/src/main/java/org/gcube/application/geoportal/service/engine/providers/ucd/UCDManager.java
@@ -18,14 +18,10 @@ import javax.ws.rs.WebApplicationException;
 import javax.ws.rs.core.Response;
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
-import java.time.temporal.TemporalAmount;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicLong;
-import java.util.concurrent.locks.*;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import static java.lang.Thread.sleep;