fixing callout serializer

git-svn-id: https://svn.wso2.org/repos/wso2/trunk/tools@182619 a5903396-d722-0410-b921-86c7d4935375
Committing the patch from AsankaS for TOOLS-1820. Thanks for the contribution

git-svn-id: https://svn.wso2.org/repos/wso2/trunk/tools@182622 a5903396-d722-0410-b921-86c7d4935375