I am wso2mb as a messaging system in my application. To get queue information from wso2mb server, I am calling rest api -
https://<Host_Name>:<Port>/services/AndesAdminService.AndesAdminServiceHttpsSoap11Endpoint/
In response to this call, I am getting sun.security.validator.ValidatorException: PKIX path validation failed exception. I checked wso2carbon.jks certificate in wso2mb, It has expired. Please let me know, What could be the solution.

You need to generate a new certificate and add it to the keystore.
https://docs.wso2.com/display/ADMIN44x/Creating+New+Keystores#CreatingNewKeystores-ca_certificateAddingCA-signedcertificatestokeystores