In my case I wanted to install subclipse, the eclipse market place is trying to connect to https://dl.bintray.com/ but resulting in to certificate error due to bad domain name. True it could be some fake sites pretending to be the trusted. But in this case, i know that this is this exact site.
“sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target”
Solution is to :
Download this certificate (I did it using chrome -> export functionality)
Add the certificate to cacerts (server trust store for java)
keytool -import -noprompt -trustcacerts -alias proxy_certficate -file /tmp/CertificateToBeTrusted -keystore /etc/pki/ca-trust/extracted/java/cacerts -storepass changeit