Checkstyle plugin SunCertPathBuilderException

Hi,

it seems that I have a problem running checkstyle task, to be more precise this is the stacktrace

    Caused by: com.puppycrawl.tools.checkstyle.api.CheckstyleException: unable to parse configuration stream
        at com.puppycrawl.tools.checkstyle.ConfigurationLoader.loadConfiguration(ConfigurationLoader.java:239)
        at com.puppycrawl.tools.checkstyle.ConfigurationLoader.loadConfiguration(ConfigurationLoader.java:181)
        at com.puppycrawl.tools.checkstyle.ant.CheckstyleAntTask.createRootModule(CheckstyleAntTask.java:425)
        ... 63 more
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:647)
        at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(XMLEntityManager.java:1305)
        at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startDTDEntity(XMLEntityManager.java:1271)
        at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.setInputSource(XMLDTDScannerImpl.java:263)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1167)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1050)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:964)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
        at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:118)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:643)
        at com.puppycrawl.tools.checkstyle.api.AbstractLoader.parseInputSource(AbstractLoader.java:104)
        at com.puppycrawl.tools.checkstyle.ConfigurationLoader.parseInputSource(ConfigurationLoader.java:150)
        at com.puppycrawl.tools.checkstyle.ConfigurationLoader.loadConfiguration(ConfigurationLoader.java:229)
        ... 65 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        ... 83 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        ... 83 more

The sample project is here: https://github.com/gajo4256/demo.
Cannot find out what exactly is causing the problem on my machine, because it works on 2 others I’ve tested. No problem adding a cert if I would know what is actually a problem here.

Any advice on what to do?
Many thnx,

Tommy

okay, it seems I’ve found the solution:

dtd schema was the problem because it was hosted on https