The junit testcase JNLPSignedResourcesHelperTest.java is using an old certificate, because there is no JRE cacert store available during test, we get a NullPointerException from Validator class:

java.lang.NullPointerException
        at java.util.HashSet.<init>(HashSet.java:116)
        at sun.security.validator.PKIXValidator.<init>(PKIXValidator.java:81)
        at sun.security.validator.Validator.getInstance(Validator.java:179)
        at com.sun.deploy.security.TrustDecider.validateChain(Unknown Source)