Define valueAs() to get the enclosed value and remove volume()

volume() is replaced by valueAs()

Change-Id: I3dbcbd6a0b8fcd28f0064272fe1fa6d7259e0a87
diff --git a/cli/src/main/java/org/onosproject/cli/net/AllocationsCommand.java b/cli/src/main/java/org/onosproject/cli/net/AllocationsCommand.java
index ccaebd4..52d9bb8 100644
--- a/cli/src/main/java/org/onosproject/cli/net/AllocationsCommand.java
+++ b/cli/src/main/java/org/onosproject/cli/net/AllocationsCommand.java
@@ -115,7 +115,7 @@
 
             for (ResourceAllocation a : allocations) {
                 print("%s%s allocated by %s", Strings.repeat(" ", level + 1),
-                                          a.resource().last(), asVerboseString(a.consumer()));
+                                          a.resource().valueAs(Object.class).orElse(""), asVerboseString(a.consumer()));
             }
         }
     }