I'm using a certificate generated with LetsEncrypt, so when I try to make a connection via HttpsUrlConnection, I get the following error:

sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested

Is there any way to install the certificate into the keystore at runtime? Or any other solutions to this issue.