diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisher.java b/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisher.java
index 606b48e..7e39264 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisher.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisher.java
@@ -3,10 +3,10 @@ package org.gcube.informationsystem.resourceregistry.publisher;
 import java.util.UUID;
 
 import org.gcube.informationsystem.model.reference.ER;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
-import org.gcube.informationsystem.model.reference.relation.ConsistsOf;
-import org.gcube.informationsystem.model.reference.relation.IsRelatedTo;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
+import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
+import org.gcube.informationsystem.model.reference.relations.IsRelatedTo;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.AlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisherImpl.java b/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisherImpl.java
index 90083a1..0aefe8b 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisherImpl.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/publisher/ResourceRegistryPublisherImpl.java
@@ -9,15 +9,15 @@ import org.gcube.common.authorization.library.provider.SecurityTokenProvider;
 import org.gcube.common.gxhttp.request.GXHTTPStringRequest;
 import org.gcube.common.scope.api.ScopeProvider;
 import org.gcube.informationsystem.model.impl.properties.HeaderImpl;
-import org.gcube.informationsystem.model.impl.utils.ISMapper;
-import org.gcube.informationsystem.model.impl.utils.Utility;
 import org.gcube.informationsystem.model.reference.ER;
-import org.gcube.informationsystem.model.reference.entity.Context;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
+import org.gcube.informationsystem.model.reference.entities.Context;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
 import org.gcube.informationsystem.model.reference.properties.Header;
-import org.gcube.informationsystem.model.reference.relation.ConsistsOf;
-import org.gcube.informationsystem.model.reference.relation.IsRelatedTo;
+import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
+import org.gcube.informationsystem.model.reference.relations.IsRelatedTo;
+import org.gcube.informationsystem.model.utils.ISMapper;
+import org.gcube.informationsystem.model.utils.Utility;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.AlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
diff --git a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/ERManagementTest.java b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/ERManagementTest.java
index 78878ae..c9c446d 100644
--- a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/ERManagementTest.java
+++ b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/ERManagementTest.java
@@ -13,18 +13,18 @@ import java.util.Map;
 import java.util.UUID;
 
 import org.gcube.informationsystem.model.impl.properties.PropagationConstraintImpl;
-import org.gcube.informationsystem.model.impl.relation.ConsistsOfImpl;
-import org.gcube.informationsystem.model.impl.relation.IsIdentifiedByImpl;
-import org.gcube.informationsystem.model.impl.utils.ISMapper;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
+import org.gcube.informationsystem.model.impl.relations.ConsistsOfImpl;
+import org.gcube.informationsystem.model.impl.relations.IsIdentifiedByImpl;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
 import org.gcube.informationsystem.model.reference.properties.PropagationConstraint;
 import org.gcube.informationsystem.model.reference.properties.PropagationConstraint.AddConstraint;
 import org.gcube.informationsystem.model.reference.properties.PropagationConstraint.RemoveConstraint;
-import org.gcube.informationsystem.model.reference.relation.ConsistsOf;
-import org.gcube.informationsystem.model.reference.relation.IsIdentifiedBy;
-import org.gcube.informationsystem.model.reference.relation.IsRelatedTo;
-import org.gcube.informationsystem.model.reference.relation.Relation;
+import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
+import org.gcube.informationsystem.model.reference.relations.IsIdentifiedBy;
+import org.gcube.informationsystem.model.reference.relations.IsRelatedTo;
+import org.gcube.informationsystem.model.reference.relations.Relation;
+import org.gcube.informationsystem.model.utils.ISMapper;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.client.Direction;
 import org.gcube.informationsystem.resourceregistry.client.ResourceRegistryClient;
diff --git a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/EntityManagementTest.java b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/EntityManagementTest.java
index adce2d2..156bf62 100644
--- a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/EntityManagementTest.java
+++ b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/EntityManagementTest.java
@@ -6,12 +6,12 @@ package org.gcube.informationsystem.resourceregistry.publisher;
 import java.util.List;
 import java.util.UUID;
 
-import org.gcube.informationsystem.model.impl.relation.IsIdentifiedByImpl;
-import org.gcube.informationsystem.model.impl.utils.ISMapper;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
-import org.gcube.informationsystem.model.reference.relation.ConsistsOf;
-import org.gcube.informationsystem.model.reference.relation.IsIdentifiedBy;
+import org.gcube.informationsystem.model.impl.relations.IsIdentifiedByImpl;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
+import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
+import org.gcube.informationsystem.model.reference.relations.IsIdentifiedBy;
+import org.gcube.informationsystem.model.utils.ISMapper;
 import org.gcube.resourcemanagement.model.impl.entity.facet.CPUFacetImpl;
 import org.gcube.resourcemanagement.model.impl.entity.facet.NetworkingFacetImpl;
 import org.gcube.resourcemanagement.model.impl.entity.facet.SoftwareFacetImpl;
diff --git a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/MultiContextTest.java b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/MultiContextTest.java
index 413a989..c28182b 100644
--- a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/MultiContextTest.java
+++ b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/MultiContextTest.java
@@ -8,9 +8,9 @@ import java.net.URL;
 import java.util.Calendar;
 import java.util.UUID;
 
-import org.gcube.informationsystem.model.impl.relation.IsIdentifiedByImpl;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.relation.IsIdentifiedBy;
+import org.gcube.informationsystem.model.impl.relations.IsIdentifiedByImpl;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.relations.IsIdentifiedBy;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
diff --git a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/RRClientTest.java b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/RRClientTest.java
index 0a6578a..a0bc6a5 100644
--- a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/RRClientTest.java
+++ b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/RRClientTest.java
@@ -6,10 +6,10 @@ package org.gcube.informationsystem.resourceregistry.publisher;
 import java.util.List;
 import java.util.UUID;
 
-import org.gcube.informationsystem.model.impl.relation.IsIdentifiedByImpl;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
-import org.gcube.informationsystem.model.reference.relation.IsIdentifiedBy;
+import org.gcube.informationsystem.model.impl.relations.IsIdentifiedByImpl;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
+import org.gcube.informationsystem.model.reference.relations.IsIdentifiedBy;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.facet.FacetNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.resource.ResourceNotFoundException;
diff --git a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/SmartgearResourcesTest.java b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/SmartgearResourcesTest.java
index 0e0bbeb..9bb22fb 100644
--- a/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/SmartgearResourcesTest.java
+++ b/src/test/java/org/gcube/informationsystem/resourceregistry/publisher/SmartgearResourcesTest.java
@@ -23,13 +23,13 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.gcube.informationsystem.model.impl.properties.HeaderImpl;
-import org.gcube.informationsystem.model.impl.relation.IsIdentifiedByImpl;
-import org.gcube.informationsystem.model.impl.utils.ISMapper;
-import org.gcube.informationsystem.model.reference.entity.Facet;
-import org.gcube.informationsystem.model.reference.entity.Resource;
+import org.gcube.informationsystem.model.impl.relations.IsIdentifiedByImpl;
+import org.gcube.informationsystem.model.reference.entities.Facet;
+import org.gcube.informationsystem.model.reference.entities.Resource;
 import org.gcube.informationsystem.model.reference.properties.Header;
-import org.gcube.informationsystem.model.reference.relation.ConsistsOf;
-import org.gcube.informationsystem.model.reference.relation.IsIdentifiedBy;
+import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
+import org.gcube.informationsystem.model.reference.relations.IsIdentifiedBy;
+import org.gcube.informationsystem.model.utils.ISMapper;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.resourcemanagement.model.impl.entity.facet.CPUFacetImpl;
 import org.gcube.resourcemanagement.model.impl.entity.facet.ContainerStateFacetImpl;