我的scala版本是2.12.8
我下载了https://developer.lightbend.com/start/?group=play&project=play-scala-rest-api-example
现在尝试做：sbt运行，但是出现以下异常。
此问题的解决方法是什么？如果我每次都犯错，那么也许是我一直想念的东西。
[error] sbt.librarymanagement.ResolveException: unresolved dependency: com.typesafe.play#sbt-plugin;2.7.0: Resolution failed several times for dependency: com.typesafe.play#sbt-plugin;2.7.0 {compile=[default(compile)]}::
[error] typesafe-ivy-releases: unable to get resource for com.typesafe.play#sbt-plugin;2.7.0: res=https://repo.typesafe.com/typesafe/ivy-releases/com.typesafe.play/sbt-plugin/scala_2.12/sbt_1.0/2.7.0/ivys/ivy.xml: 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
[error] sbt-plugin-releases: unable to get resource for com.typesafe.play#sbt-plugin;2.7.0: res=https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/com.typesafe.play/sbt-plugin/scala_2.12/sbt_1.0/2.7.0/ivys/ivy.xml: 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