ADDITIONAL SYSTEM INFORMATION :
Microsoft Windows [Version 6.1.7601]

java version "11-ea" 2018-09-25
Java(TM) SE Runtime Environment 18.9 (build 11-ea+17)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11-ea+17, mixed mode)

A DESCRIPTION OF THE PROBLEM :
When I run java program with Oracle JDK 10.0.1 it works fine.
When I run same program with Oracle JDK 11-ea+17 it fails with exception.

REGRESSION : Last worked in version 10.0.1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run following java program


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It prints response from HTTP post request:
{"error":{"error_code":5,"error_msg":"User authorization failed: no access_token passed.","request_params":[{"key":"oauth","value":"1"},{"key":"method","value":"groups.getById"},{"key":"group_ids","value":"1"}]}}
ACTUAL -
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
at java.base/sun.security.ssl.Alerts.getSSLException(Alerts.java:198)
at java.base/sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1974)
at java.base/sun.security.ssl.Handshaker.fatalSE(Handshaker.java:345)
at java.base/sun.security.ssl.Handshaker.fatalSE(Handshaker.java:339)
at java.base/sun.security.ssl.ClientHandshaker.checkServerCerts(ClientHandshaker.java:1968)
at java.base/sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1777)
at java.base/sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:264)
at java.base/sun.security.ssl.Handshaker.processLoop(Handshaker.java:1098)
at java.base/sun.security.ssl.Handshaker.processRecord(Handshaker.java:1026)
at java.base/sun.security.ssl.SSLSocketImpl.processInputRecord(SSLSocketImpl.java:1137)
at java.base/sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1074)
at java.base/sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:973)
at java.base/sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1402)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1429)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1413)
at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:567)
at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:163)
at main.java.VkApiCall.main(VkApiCall.java:15)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:290)
at java.base/sun.security.validator.Validator.validate(Validator.java:264)
at java.base/sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:343)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:226)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:133)
at java.base/sun.security.ssl.ClientHandshaker.checkServerCerts(ClientHandshaker.java:1947)
... 14 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
at java.base/sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
at java.base/java.security.cert.CertPathBuilder.build(CertPathBuilder.java:297)
at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
... 20 more

---------- BEGIN SOURCE ----------
import java.io.*;
import java.net.*;

public class VkApiCall {
    public static void main(String[] args) throws IOException {
        URL url = new URL("https://api.vk.com/method/groups.getById");
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setRequestMethod("POST");
        con.setDoInput(true);
        con.setDoOutput(true);
        byte[] out = "group_ids=1".getBytes("UTF-8");
        con.setFixedLengthStreamingMode(out.length);
        con.connect();
        try (OutputStream os = con.getOutputStream()) {
            os.write(out);
        }
        InputStream inputStream = con.getInputStream();
        byte[] bytes = inputStream.readAllBytes();
        System.out.println(new String(bytes, "UTF-8"));
    }
}
---------- END SOURCE ----------

FREQUENCY : always