implement null validation for resource uuid in base command

Author: erikbocks

api/src/main/java/org/apache/cloudstack/api/BaseCmd.java

@@ -503,7 +503,7 @@ public Map<String, String> convertExternalDetailsToMap(Map externalDetails) {
     public String getResourceUuid(String parameterName) {
         String resourceUuid = CallContext.current().getApiResourceUuid(parameterName);
 
-        if (UuidUtils.isUuid(resourceUuid)) {
+        if (resourceUuid != null && UuidUtils.isUuid(resourceUuid)) {
             return resourceUuid;
         }