Added missing documentation

src/main/java/org/gcube/resourcemanagement/model/reference/relations/isrelatedto/Hosts.java

@@ -35,7 +35,14 @@ import org.gcube.resourcemanagement.model.reference.entities.resources.VirtualMa
 @JsonDeserialize(as=HostsImpl.class)
 @TypeMetadata(
 	name = Hosts.NAME, 
-	description = "",
+	description = "Hosts relation is used from a {@link Site} a {@link Service} instance.\n"
+			+ "The target of the Hosts relation depends on the service offered by the Site.\n"
+			+ "When the resources provided by a site are virtual machines, "
+			+ "Hosts relation is created from a {@link Site} to a {@link VirtualMachine}.\n"
+			+ "When, instead a Site provides web-services, Hosts relation is created with {@link EService}.\n"
+			+ "If a site provides container facilities Hosts relation is created with {@link HostingNode}.\n"
+			+ "By defining Hosts relation with target {@link Service}, the model is capable of representing "
+			+ "the diverse type of federated systems and service.",
 	version = TypeVersion.MINIMAL_VERSION_STRING
 )
 @Change(version = TypeVersion.MINIMAL_VERSION_STRING, description = TypeVersion.MINIMAL_VERSION_DESCRIPTION)

src/main/java/org/gcube/resourcemanagement/model/reference/relations/isrelatedto/Involves.java

@@ -23,7 +23,7 @@ import org.gcube.resourcemanagement.model.reference.entities.resources.Dataset;
 @JsonDeserialize(as=InvolvesImpl.class)
 @TypeMetadata(
 	name = Involves.NAME, 
-	description = "",
+	description = "Involves is used to indicate that and {@link Actor} is involved in a {@link Dataset}.",
 	version = TypeVersion.MINIMAL_VERSION_STRING
 )
 @Change(version = TypeVersion.MINIMAL_VERSION_STRING, description = TypeVersion.MINIMAL_VERSION_DESCRIPTION)

src/main/java/org/gcube/resourcemanagement/model/reference/relations/isrelatedto/Uses.java

@@ -23,7 +23,9 @@ import org.gcube.resourcemanagement.model.reference.entities.resources.EService;
 @JsonDeserialize(as=UsesImpl.class)
 @TypeMetadata(
 	name = Uses.NAME, 
-	description = "",
+	description = "Uses relation inform regarding the network invocation of the target"
+			+ "{@link EService} by the source.\n"
+			+ "Uses relation specialises the semantic of {@link CallsFor}.",
 	version = TypeVersion.MINIMAL_VERSION_STRING
 )
 @Change(version = TypeVersion.MINIMAL_VERSION_STRING, description = TypeVersion.MINIMAL_VERSION_DESCRIPTION)