连接到cloudant数据库时，出现以下异常：
Caused by: java.security.cert.CertificateException: PKIX path building
failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at com.ibm.ws.ssl.core.WSX509TrustManager.checkServerTrusted(WSX509TrustManager.java:322)
at [internal classes]
at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:992)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1596)
... 25 more
请问问题是什么以及如何解决？