[ERROR] Failed to execute goal on project UnleashedSkills: Could not resolve dependencies for project net.ulmc:UnleashedSkills:jar:1.0: Failed to collect dependencies at org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT: Failed to read artifact descriptor for org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT: Could not transfer artifact org.spigotmc:spigot-api:pom:1.11.2-R0.1-SNAPSHOT from/to ulmc-repo (https://repo.ulmc.net): sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal on project UnleashedSkills: Could not resolve dependencies for project net.ulmc:UnleashedSkills:jar:1.0: Failed to collect dependencies at org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.getDependencies(LifecycleDependencyResolver.java:221)
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.resolveProjectDependencies(LifecycleDependencyResolver.java:127)
        at org.apache.maven.lifecycle.internal.MojoExecutor.ensureDependenciesAreResolved(MojoExecutor.java:245)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:199)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
        at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.project.DependencyResolutionException: Could not resolve dependencies for project net.ulmc:UnleashedSkills:jar:1.0: Failed to collect dependencies at org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT
        at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve(DefaultProjectDependenciesResolver.java:180)
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.getDependencies(LifecycleDependencyResolver.java:195)
        ... 23 more
Caused by: org.eclipse.aether.collection.DependencyCollectionException: Failed to collect dependencies at org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.collectDependencies(DefaultDependencyCollector.java:291)
        at org.eclipse.aether.internal.impl.DefaultRepositorySystem.collectDependencies(DefaultRepositorySystem.java:316)
        at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve(DefaultProjectDependenciesResolver.java:172)
        ... 24 more
Caused by: org.eclipse.aether.resolution.ArtifactDescriptorException: Failed to read artifact descriptor for org.spigotmc:spigot-api:jar:1.11.2-R0.1-SNAPSHOT
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:282)
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:198)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.resolveCachedArtifactDescriptor(DefaultDependencyCollector.java:535)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.getArtifactDescriptorResult(DefaultDependencyCollector.java:519)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.processDependency(DefaultDependencyCollector.java:409)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.processDependency(DefaultDependencyCollector.java:363)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.process(DefaultDependencyCollector.java:351)
        at org.eclipse.aether.internal.impl.DefaultDependencyCollector.collectDependencies(DefaultDependencyCollector.java:254)
        ... 26 more
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Could not transfer artifact org.spigotmc:spigot-api:pom:1.11.2-R0.1-SNAPSHOT from/to ulmc-repo (https://repo.ulmc.net): sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:444)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:246)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:223)
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:267)
        ... 33 more
Caused by: org.eclipse.aether.transfer.ArtifactTransferException: Could not transfer artifact org.spigotmc:spigot-api:pom:1.11.2-R0.1-SNAPSHOT from/to ulmc-repo (https://repo.ulmc.net): sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at org.eclipse.aether.connector.basic.ArtifactTransportListener.transferFailed(ArtifactTransportListener.java:43)
        at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:355)
        at org.eclipse.aether.util.concurrency.RunnableErrorForwarder$1.run(RunnableErrorForwarder.java:67)
        at org.eclipse.aether.connector.basic.BasicRepositoryConnector$DirectExecutor.execute(BasicRepositoryConnector.java:581)
        at org.eclipse.aether.connector.basic.BasicRepositoryConnector.get(BasicRepositoryConnector.java:249)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:520)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:421)
        ... 36 more
Caused by: org.apache.maven.wagon.TransferFailedException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at org.apache.maven.wagon.providers.http.AbstractHttpClientWagon.fillInputData(AbstractHttpClientWagon.java:1066)
        at org.apache.maven.wagon.providers.http.AbstractHttpClientWagon.fillInputData(AbstractHttpClientWagon.java:960)
        at org.apache.maven.wagon.StreamWagon.getInputStream(StreamWagon.java:116)
        at org.apache.maven.wagon.StreamWagon.getIfNewer(StreamWagon.java:88)
        at org.apache.maven.wagon.StreamWagon.get(StreamWagon.java:61)
        at org.eclipse.aether.transport.wagon.WagonTransporter$GetTaskRunner.run(WagonTransporter.java:560)
        at org.eclipse.aether.transport.wagon.WagonTransporter.execute(WagonTransporter.java:427)
        at org.eclipse.aether.transport.wagon.WagonTransporter.get(WagonTransporter.java:404)
        at org.eclipse.aether.connector.basic.BasicRepositoryConnector$GetTaskRunner.runTask(BasicRepositoryConnector.java:447)
        at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:350)
        ... 41 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 sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
        at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509)
        at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
        at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
        at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
        at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
        at org.apache.maven.wagon.providers.http.httpclient.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:275)
        at org.apache.maven.wagon.providers.http.httpclient.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:254)
        at org.apache.maven.wagon.providers.http.httpclient.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:123)
        at org.apache.maven.wagon.providers.http.httpclient.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:318)
        at org.apache.maven.wagon.providers.http.httpclient.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:363)
        at org.apache.maven.wagon.providers.http.httpclient.impl.execchain.MainClientExec.execute(MainClientExec.java:219)
        at org.apache.maven.wagon.providers.http.httpclient.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
        at org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec.execute(RetryExec.java:86)
        at org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
        at org.apache.maven.wagon.providers.http.httpclient.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
        at org.apache.maven.wagon.providers.http.httpclient.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
        at org.apache.maven.wagon.providers.http.AbstractHttpClientWagon.execute(AbstractHttpClientWagon.java:832)
        at org.apache.maven.wagon.providers.http.AbstractHttpClientWagon.fillInputData(AbstractHttpClientWagon.java:983)
        ... 50 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
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
        at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
        at sun.security.validator.Validator.validate(Validator.java:260)
        at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
        at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491)
        ... 70 more
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:146)
        at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:131)
        at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
        ... 76 more