engine/orchestration: display numeric value instead of variable name (#3818)

If the disk size of the vm to be created is greater
than the volume size, then the exception message should
display the numeric value instead of variable name

Author: ravening

engine/orchestration/src/main/java/org/apache/cloudstack/engine/orchestration/VolumeOrchestrator.java

@@ -645,7 +645,7 @@ public boolean validateVolumeSizeRange(long size) {
         if (size < 0 || (size > 0 && size < (1024 * 1024 * 1024))) {
             throw new InvalidParameterValueException("Please specify a size of at least 1 GB.");
         } else if (size > (MaxVolumeSize.value() * 1024 * 1024 * 1024)) {
-            throw new InvalidParameterValueException("volume size " + size + ", but the maximum size allowed is " + MaxVolumeSize + " GB.");
+            throw new InvalidParameterValueException("volume size " + size + ", but the maximum size allowed is " + MaxVolumeSize.value() + " GB.");
         }
 
         return true;