Error running webservice_proxy_security.

When running webservice_proxy_security QS the following exception is thrown on the client side:

runinternal:
[java] **** REQUEST URL: https://localhost:8443/Quickstart_webservice_proxy_security/http/ProxyWS
[java] **** REQUEST BODY: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:hello="http://webservice_proxy_security/helloworld"><soapenv:Header/><soapenv:Body><hello:sayHello><toWhom>mbaluch</toWhom></hello:sayHello></soapenv:Body></soapenv:Envelope>
[java] 14:12:09,151 DEBUG [main][header] >> "POST /Quickstart_webservice_proxy_security/http/ProxyWS HTTP/1.1[\r][\n]"
[java] 14:12:09,170 DEBUG [main][header] >> "Content-Type: text/xml;charset=UTF-8[\r][\n]"
[java] 14:12:09,170 DEBUG [main][header] >> "Authorization: Basic a2VybWl0OnRoZWZyb2c=[\r][\n]"
[java] 14:12:09,170 DEBUG [main][header] >> "SOAPAction: ""[\r][\n]"
[java] 14:12:09,170 DEBUG [main][header] >> "User-Agent: Jakarta Commons-HttpClient/3.0.1[\r][\n]"
[java] 14:12:09,171 DEBUG [main][header] >> "Host: localhost:8443[\r][\n]"
[java] 14:12:09,171 DEBUG [main][header] >> "Content-Length: 256[\r][\n]"
[java] 14:12:09,171 DEBUG [main][header] >> "[\r][\n]"
[java] 14:12:09,171 DEBUG [main][content] >> "<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:hello="http://webservice_proxy_security/helloworld"><soapenv:Header/><soapenv:Body><hello:sayHello><toWhom>mbaluch</toWhom></hello:sayHello></soapenv:Body></soapenv:Envelope>"
[java] Exception in thread "main" 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
[java] at com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Alerts.java:174)
[java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1611)
[java] at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:187)
[java] at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:181)
[java] at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1035)
[java] at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:124)
[java] at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:516)
[java] at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:454)
[java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:884)
[java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1112)
[java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:623)
[java] at com.sun.net.ssl.internal.ssl.AppOutputStream.write(AppOutputStream.java:59)
[java] at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
[java] at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
[java] at java.io.FilterOutputStream.flush(FilterOutputStream.java:123)
[java] at org.apache.commons.httpclient.methods.StringRequestEntity.writeRequest(StringRequestEntity.java:150)
[java] at org.apache.commons.httpclient.methods.EntityEnclosingMethod.writeRequestBody(EntityEnclosingMethod.java:495)
[java] at org.apache.commons.httpclient.HttpMethodBase.writeRequest(HttpMethodBase.java:1973)
[java] at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:993)
[java] at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:397)
[java] at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:170)
[java] at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:396)
[java] at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:324)
[java] at org.jboss.soa.esb.samples.quickstart.webservice_proxy_security.test.SendWSMessage.main(SendWSMessage.java:89)
[java] Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[java] at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:285)
[java] at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:191)
[java] at sun.security.validator.Validator.validate(Validator.java:218)
[java] at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:126)
[java] at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:209)
[java] at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:249)
[java] at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1014)
[java] ... 19 more
[java] Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[java] at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:174)
[java] at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:238)
[java] at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:280)
[java] ... 25 more