Getting error while uploading the file using Java

Create Folder is working, but Upload file is not working.

Upload URL - https://upload.box.com/api/2.0/files/content

Error -

--------

Caused by: com.box.sdk.BoxAPIException: Couldn't connect to the Box API due to a network error.
at com.box.sdk.BoxMultipartRequest.writeBody(BoxMultipartRequest.java:171) ~[box-java-sdk-2.32.0.jar:na]
at com.box.sdk.BoxAPIRequest.trySend(BoxAPIRequest.java:545) ~[box-java-sdk-2.32.0.jar:na]
at com.box.sdk.BoxAPIRequest.send(BoxAPIRequest.java:354) ~[box-java-sdk-2.32.0.jar:na]
at com.box.sdk.BoxAPIRequest.send(BoxAPIRequest.java:329) ~[box-java-sdk-2.32.0.jar:na]
at com.box.sdk.BoxFolder.uploadFile(BoxFolder.java:551) ~[box-java-sdk-2.32.0.jar:na]
at com.box.sdk.BoxFolder.uploadFile(BoxFolder.java:456) ~[box-java-sdk-2.32.0.jar:na]
at com.box.app.ConsumeBOX2.createFolder(ConsumeBOX2.java:156) ~[classes/:na]
at com.box.app.ConsumeBOX2.uploadFile(ConsumeBOX2.java:252) ~[classes/:na]
at com.box.app.BoxApiApplication.run(BoxApiApplication.java:75) [classes/:na]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:784) [spring-boot-2.2.7.RELEASE.jar:2.2.7.RELEASE]
... 5 common frames omitted
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 sun.security.ssl.Alerts.getSSLException(Alerts.java:198) ~[na:1.8.0_251]
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1967) ~[na:1.8.0_251]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:331) ~[na:1.8.0_251]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:325) ~[na:1.8.0_251]
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1689) ~[na:1.8.0_251]
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:226) ~[na:1.8.0_251]
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1082) ~[na:1.8.0_251]
at sun.security.ssl.Handshaker.process_record(Handshaker.java:1010) ~[na:1.8.0_251]
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1079) ~[na:1.8.0_251]
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1388) ~[na:1.8.0_251]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1416) ~[na:1.8.0_251]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1400) ~[na:1.8.0_251]
at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559) ~[na:1.8.0_251]
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185) ~[na:1.8.0_251]
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1340) ~[na:1.8.0_251]
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1315) ~[na:1.8.0_251]
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java:264) ~[na:1.8.0_251]
at com.box.sdk.BoxMultipartRequest.writeBody(BoxMultipartRequest.java:139) ~[box-java-sdk-2.32.0.jar:na]
... 14 common frames omitted
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 sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:450) ~[na:1.8.0_251]
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:317) ~[na:1.8.0_251]
at sun.security.validator.Validator.validate(Validator.java:262) ~[na:1.8.0_251]
at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:330) ~[na:1.8.0_251]
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:227) ~[na:1.8.0_251]
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132) ~[na:1.8.0_251]
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1671) ~[na:1.8.0_251]
... 27 common frames omitted
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141) ~[na:1.8.0_251]
at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126) ~[na:1.8.0_251]
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280) ~[na:1.8.0_251]
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:445) ~[na:1.8.0_251]